Vitamin D for COVID-19: real-time analysis of 596 studies

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Vitamin D for COVID-19

138 studies with >200,000 patients

Serious outcome risk

Vitamin D

Control

Significantly lower risk for mortality, ICU, hospitalization, progression, recovery, cases, and viral clearance.

56% lower risk for early treatment CI 37-70%

35% lower risk in 41 RCTs CI 23-45%

39% lower mortality in 79 studies CI 32-45%

COVID-19 Vitamin D studies · October 2026

Outcome (studies)

Improvement

Relative risk · 95% CI

All studies (138)38%

With exclusions (102)42%

Mortality (79)39%

Hospitalization (27)22%

Cases (33)18%

RCTs (41)35%

RCT mortality (24)38%

Cholecalciferol (52)43%

Calcitriol etc. (9)66%

Prophylaxis (65)32%

Early (12)56%

Late (61)47%

00.511.5+

← Vitamin D
reduces riskIncreased
risk →

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Ongoing treatment with multiple doses is more effective than single bolus doses, and calcitriol/calcifediol and analogs are more effective than cholecalciferol1. vitamind4all.org2 provides treatment recommendations. Vitamin D was adopted in 18 countries. Recent:

di Filippo

Almacioglu

Yang

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	Covid Analysis	Vitamin D reduces COVID-19 risk: real-time meta-analysis of 370 studies (138 treatment studies and 232 sufficiency studies) (Version 340)
	Significantly lower risk is seen for mortality, ICU admission, hospitalization, and cases. 75 studies from 69 independent teams in 25 countries show significantly lower risk. Meta-analysis using the most serious outcome reported shows..
Jun 10	di Filippo et al., Endocrine, doi:10.1007/s12020-026-04677-6	Impact of chronic cholecalciferol supplementation and vitamin D status on risk of post-vaccination SARS-CoV-2 breakthrough infection
	50% fewer symptomatic cases (p=0.12). Retrospective 114 vaccinated outpatients showing lower risk of symptomatic COVID-19 cases with adequate vitamin D status and cholecalciferol supplementation (there was a similar point estimate for the full and matched populations, but wit..
May 13	Almacioglu et al., International Journal of Molecular Sciences, doi:10.3390/ijms27104393	Association of Serum Vitamin D and Hematological Parameters with SARS-CoV-2 PCR Positivity: A Combined Biomarker Approach in Asymptomatic Children
	53% fewer cases (p=0.0003). Retrospective 127 asymptomatic children with household COVID-19 exposure, showing lower vitamin D levels independently associated with SARS-CoV-2 PCR positivity.
May 13	Yang et al., Heliyon, doi:10.1016/j.heliyon.2026.e44988	Vitamin D supplementation benefits COVID-19: A systematic review and meta-analysis
	Systematic review and meta-analysis of 20 RCTs (n = 2,756) showing significantly lower mortality and ICU admission with vitamin D treatment for COVID-19.
Apr 16	Rizzi et al., International Journal of Molecular Sciences, doi:10.3390/ijms27083541	Higher 25(OH)D Levels at Admission Predict a Favorable Disease Evolution in Moderate-to-Severe COVID-19 Patients
	59% improved recovery (p=0.04). Prospective observational cohort study of 139 hospitalized moderate-to-severe COVID-19 patients showing that higher baseline vitamin D levels predict favorable clinical outcomes.
Apr 15	Abbas et al., PLOS One, doi:10.1371/journal.pone.0346978	Acute SARS-CoV-2 viral load and systemic inflammation are associated with neuropsychiatric and musculoskeletal symptoms in long COVID
	26% lower long COVID (p=0.11). Retrospective 300 COVID-19 outpatients in Pakistan showing that 59% met criteria for long COVID at 10 months post-infection, with neuropsychiatric symptoms (35%) and musculoskeletal symptoms (32.2%) being the most common. In multivariable..
Apr 8	Younes, S., Next Research, doi:10.1016/j.nexres.2026.101727	The influence of micronutrients on olfactory dysfunction associated with COVID-19 and long COVID
	Review of the influence of micronutrients on olfactory dysfunction associated with COVID-19 and long COVID. Author investigates how dietary supplements like vitamins A, B, C, D, E, zinc, and alpha-lipoic acid can help restore the sense of..
Mar 23	di Filippo et al., Journal of Endocrinological Investigation, doi:10.1007/s40618-026-02858-8	Chronic cholecalciferol supplementation and adequate vitamin D status are associated with reduced risk of Long COVID
	78% lower long COVID (p=0.02). Retrospective 132 COVID-19 patients showing lower long COVID risk with chronic cholecalciferol supplementation. The study compared patients receiving long-term cholecalciferol for at least 24 months to those without supplementation, track..
Mar 12	Ganmaa et al., The Journal of Nutrition, doi:10.1016/j.tjnut.2026.101398	A Randomized Trial of Vitamin D Supplementation and COVID-19 Clinical Outcomes and Long COVID: The Vitamin D for COVID-19 Trial
	4% improvement (p=0.76), 17% lower long COVID (p=0.24), and 71% higher transmission (p=0.21). VIVID trial - results were withheld without explanation for over 3 years, until long after the end of the pandemic. There is no scientific or ethical justification for withholding results this long. There are many serious anomolies in the..
Feb 28	Adetunji et al., BMC Infectious Diseases, doi:10.1186/s12879-026-12959-7	Association between serum vitamins and COVID-19 infection: a cross-sectional study of healthcare workers in a Nigerian tertiary hospital
	Cross-sectional study of 181 healthcare workers showing significantly lower serum levels of most vitamins (A, C, D, E, and B-complex vitamins except B12) in those with COVID-19 infection compared to uninfected controls. Authors hypothesiz..
Feb 16	McLindon et al., American Journal of Therapeutics, doi:10.1097/MJT.0000000000002118	Safety and Tolerability of Multimodal Therapy (Ivermectin, Doxycycline, Vitamin C, Vitamin D, and Zinc) With or Without Famotidine in Australian Patients With COVID-19 Infection: A Pilot Cohort Trial
	RCT 275 outpatients showing very low hospitalization with combination therapy including ivermectin, doxycycline, vitamin C, vitamin D3, and zinc, with or without famotidine. There was no control group. Only 4 patients were hospitalized wi..
Feb 5	Chen et al., MDPI AG, doi:10.20944/preprints202602.0361.v1	Vitamin D3 Supplementation Enhances Symptom Relief and Modulates Microbiome and Immune Responses in Pediatric Post-Acute Sequelae of COVID-19: A Randomized Controlled Trial
	RCT 33 pediatric outpatients with post-acute sequelae of COVID-19 (PASC) showing significant symptom improvement with vitamin D3 treatment.
Jan 31	Awla et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2025.106879	Vitamin D pathway as a multi-level predictor of COVID-19 severity and mortality: Integrating serum levels, FokI (rs2228570) VDR polymorphism, and lung tissue expression
	Prospective case-control study of 95 COVID-19 patients and 75 healthy controls in Iraq showing strong associations between vitamin D deficiency, VDR gene polymorphism, and COVID-19 severity and mortality.
Jan 12	Zendehdel et al., Research Square, doi:10.21203/rs.3.rs-8254002/v1	Investigation of the prevalence of vitamin D deficiency in hospitalized COVID-19 patients and its association with disease severity, outcome, and mortality
	66% lower mortality (p=0.04), 26% lower ventilation (p=0.67), and 48% lower ICU admission (p=0.16). Retrospective 276 hospitalized COVID-19 patients showing higher mortality with vitamin D deficiency. The main analysis found no significant differences in ICU admission, mechanical ventilation, or mortality, however comparing severely def..
Dec 26	Doustmohammadian et al., Nutrition Clinique et Métabolisme, doi:10.1016/j.nupar.2025.12.001	Impact of vitamin D supplementation on COVID-19 mortality: A systematic review and meta-analysis
	33% lower mortality (p=0.04). Systematic review and meta analysis of 24 studies showing significantly lower COVID-19 mortality with vitamin D treatment.
Dec 25 2025	Jazar et al., Pakistan Journal of Biological Sciences, doi:10.3923/pjbs.2025.640.648	Role of Vitamin D Levels in COVID-19 Disease Severity: A Multicenter Retrospective Study from Qatar
	21% lower mortality (p=0.78), 43% shorter ICU admission (p=0.04), and 20% shorter hospitalization (p=0.23). Retrospective 296 hospitalized COVID-19 patients in Qatar showing longer ICU stays with vitamin D deficiency. No significant difference was found for hospital length of stay or mortality.
Dec 23 2025	Khajebishak et al., BMC Infectious Diseases, doi:10.1186/s12879-025-12297-0	Nutritional and inflammatory biomarkers for COVID-19 susceptibility: a focus on vitamin D, potassium, and hematological indices
	Case-control study of 394 participants (234 COVID-19 patients and 160 controls) showing lower vitamin D and potassium levels associated with increased COVID-19 infection risk. Each unit increase in vitamin D reduced COVID-19 risk by 3%. A..
Dec 10 2025	Meltzer et al., Clinical Nutrition, doi:10.1016/j.clnu.2026.106722 (results released 12/10/2025)	Effect of moderate or high versus low dose daily vitamin D on COVID-19 incidence: A double-blind, parallel-group randomized clinical trial
	27% fewer cases (p=0.09) and 63% fewer symptomatic cases (p=0.06). RCT 923 adults in the USA showing lower COVID-19 incidence with 4,000 IU/day vitamin D compared with 400 IU/day (aHR 0.62, p=0.045), but no significant benefit with 10,000 IU/day (aHR 0.99). The prespecified pooled comparison of 4,000/10,..
Oct 7 2025	Adhora et al., Discover Social Science and Health, doi:10.1007/s44155-025-00303-4	The role of diet and micronutrient supplementation in COVID-19 recovery: a cross-sectional survey of Bangladeshi patients
	Retrospective 384 COVID-19 patients in Bangladesh showing shorter recovery time associated with the use of vitamin C, D, and zinc, balanced diet intake, and normal BMI.
Oct 1 2025	Nahhas et al., International Journal of Medicine in Developing Countries, doi:10.24911/IJMDC.51-1747240075	Investigating the relationship between vitamin D levels and COVID-19 severity among patients at MNGHA in Saudi Arabia
	51% lower hospitalization (p=0.29). Cross-sectional study of 471 COVID-19 patients in Saudi Arabia showing no significant association between vitamin D levels and COVID-19 severity in unadjusted results.
Sep 29 2025	Begum et al., Journal of Family Medicine and Primary Care, doi:10.4103/jfmpc.jfmpc_2017_24	Prevalence and risk factors for post-COVID-19 syndrome on medical students in Tabuk, Saudi Arabia-2023-2024
	59% lower long COVID (p=0.01). Retrospective 424 medical students in Saudi Arabia showing vitamin D deficiency, diabetes, and bronchial asthma significantly associated with long COVID.
Sep 23 2025	Roth et al., Frontiers in Cellular and Infection Microbiology, doi:10.3389/fcimb.2025.1671738	Vitamin D-inducible antimicrobial peptide LL-37 binds SARS-CoV-2 Spike and accessory proteins ORF7a and ORF8
	In vitro study showing that vitamin D-inducible antimicrobial peptide LL-37 binds to multiple SARS-CoV-2 proteins and inhibits viral entry.
Sep 18 2025	Matangkha et al., Medical Sciences, doi:10.3390/medsci13030199	Association Between Vitamin D Levels and Long COVID Signs and Symptoms
	83% lower long COVID (p=0.0007). Retrospective 170 outpatients with mild COVID-19 showing higher risk of long COVID with vitamin D deficiency.
Sep 16 2025	Bleffgen et al., Frontiers in Nutrition, doi:10.3389/fnut.2025.1608300	Micronutrient status and fatty acid profile of adults with SARS-CoV-2 infection—an observational study
	Retrospective 139 SARS-CoV-2 positive patients (62 hospitalized, 77 home care) and 314 healthy controls showing alterations in fatty acid profiles but similar overall micronutrient levels compared to controls. When stratified by disease s..
Sep 12 2025	Sheng et al., Journal of the Chinese Medical Association, doi:10.1097/JCMA.0000000000001294	Association between vitamin D and COVID-19 infection and mortality in Taiwanese patients
	91% lower mortality (p=0.04). Retrospective 481 symptomatic adults in Taiwan showing higher mortality among COVID-19-positive patients with vitamin D deficiency. There was no crude association between vitamin D level and infection risk, however infection was analyzed ..
Aug 25 2025	García-Marín et al., ACS Omega, doi:10.1021/acsomega.5c05175	Exploring SARS-CoV-2 Spike RBD Pockets as Targets for Generic Drugs: A Combined Computational, Biophysical, and Biological Approach
	In silico and in vitro study showing that fingolimod inhibits SARS-CoV-2 infection by binding to the spike protein receptor binding domain (RBD). Fingolimod showed the strongest binding affinity to both Wuhan-Hu-1 and Omicron BA.1 variant..
Aug 18 2025	Jaurrieta-Largo et al., International Journal of Molecular Sciences, doi:10.3390/ijms26167975	A Machine Learning Approach to Understanding the Genetic Role in COVID-19 Prognosis: The Influence of Gene Polymorphisms Related to Inflammation, Vitamin D, and ACE2
	Retrospective 338 hospitalized COVID-19 patients in Spain showing that genetic polymorphisms in inflammation, vitamin D, and ACE2-related genes can predict COVID-19 pneumonia, mortality, and rehospitalization with high accuracy.
Aug 2 2025	Vercellino et al., Pathogens, doi:10.3390/pathogens14080765	Influence of Sex and 1,25α Dihydroxyvitamin D3 on SARS-CoV-2 Infection and Viral Entry
	In vitro study showing that calcitriol and 17β-estradiol (E2) inhibit SARS-CoV-2 in Vero E6 cells. Authors treated cells with 100 nM of E2 and calcitriol for 15 days before infection with VSV-based pseudovirus SARS-CoV-2 and wild-type D61..
Jul 31 2025	Hazan et al., American Journal of Infectious Diseases, doi:10.3844/ajidsp.2026.4.26 (date from preprint)	Rapid Recovery of Peripheral Oxygen Saturation in Hypoxic COVID-19 Patients With Ivermectin/Doxycycline/Zinc Multidrug Therapy
	Retrospective 26 consecutive severe COVID-19 outpatients with hypoxia (25 with SpO₂ ≤90%) showing rapid oxygen saturation recovery and survival with ivermectin/doxycycline/zinc/vitamin C/vitamin D combination therapy. All 24 patients comp..
Jul 23 2025	Chen et al., Research Square, doi:10.21203/rs.3.rs-7146347/v1	Vitamin D blood levels and vitamin D receptor polymorphisms contribute to post-acute sequelae of severe acute respiratory syndrome coronavirus 2 severity in the pediatric patients
	Analysis of 123 pediatric patients with post-acute sequelae of SARS-CoV-2 (PASC) showing that both low vitamin D levels and VDR genetic variants contribute to increased symptom severity.
Jul 18 2025	Monroy-Iglesias et al., PLoS One, doi:10.1371/journal.pone.0328232	Effects of vitamin D on COVID-19 risk and hospitalisation in the UK biobank
	26% lower hospitalization (p<0.0001) and 5% more cases (p=0.03). Case-control analysis of 151,543 UK Biobank participants showing higher odds of COVID-19 hospitalisation for those with low baseline serum vitamin D, and slightly lower risk of cases. Vitamin D measurements were taken a decade before the ..
Jul 15 2025	Al-Khrasani et al., Biomedicine & Pharmacotherapy, doi:10.1016/j.biopha.2025.118346	Do vitamins halt the COVID-19-evoked pro-inflammatory cytokines involved in the development of neuropathic pain?
	Review of vitamin supplementation for COVID-19-evoked pro-inflammatory cytokines involved in neuropathic pain development. Authors examine how certain vitamins may help prevent post-COVID neuropathic pain by modulating pro-inflammatory cy..
Jul 6 2025	Kow et al., Nutrition in Clinical Practice, doi:10.1002/ncp.11349	Vitamin D and COVID‐19: How much more evidence do we need?
	Discussion of clinical evidence supporting vitamin D treatment for COVID-19. Authors highlight [Vasconcelos] showing reduced all-cause mortality, and cite their own systematic review and meta-analysis of 19 RCTs that found a significant ..
Jun 27 2025	Madar et al., COVID, doi:10.3390/covid5070097	Vitamin D Status and SARS-CoV-2 Positivity in Lebanon Among Adults: A Cross-Sectional Study in South Lebanon
	34% fewer cases (p=0.15). Cross-sectional study of 384 adults showing no significant association between vitamin D levels and test positivity.
Jun 24 2025	Li et al., Journal of Inflammation Research, doi:10.2147/JIR.S522566	Association Between Vitamin A and D Status and the Risk of COVID-19 in the Elderly Population: A Single-Center Experience
	6% fewer cases (p=0.31). Prospective study of 32 elderly COVID-19 patients and 30 healthy controls in China showing significantly lower vitamin A and D levels in COVID-19 patients. In multivariable analysis, vitamin A deficiency was associated with significantly ..
Jun 18 2025	Chen et al., Frontiers in Nutrition, doi:10.3389/fnut.2025.1583276	Association between vitamin D deficiency and clinical outcome in patients with COVID-19 in the post-Omicron phase
	61% lower mortality (p=0.007). TriNetX PSM retrospective showing that vitamin D deficiency was significantly associated with increased 30-day mortality and adverse outcomes in COVID-19 patients, although the magnitude of this association decreased in the post-Omicron p..
Jun 10 2025	Blázquez-Cabrera et al., Nutrients, doi:10.3390/nu17121968	ALBACOVIDIOL Study: Effect of Calcifediol Treatment on Mortality in Patients Hospitalized for COVID-19: A Retrospective Analysis
	52% lower mortality (p=0.05). Retrospective 230 hospitalized COVID-19 patients in Spain, showing lower mortality with calcifediol treatment (p = 0.053).
May 31 2025	Wagner et al., Clinical Nutrition Open Science, doi:10.1016/j.nutos.2025.05.007	Exploring the association between vitamin D status and Corona Virus-19 infection in a cohort of adults aged 50 years and older
	74% fewer cases (p=0.01). Prospective study of 131 adults aged 50+ years showing lower vitamin D status was significantly associated with higher risk of COVID-19 infection and hospitalization. Adjusted results based on deficiency are only provided for cases (other..
May 26 2025	Bigman et al., Nutrients, doi:10.3390/nu17111802	A Comprehensive Scoping Review on Diet and Nutrition in Relation to Long COVID-19 Symptoms and Recovery
	Scoping review of 50 studies (27 interventional, 23 observational) examining the role of diet and nutrition in long COVID-19 symptom management and recovery. Approximately 76% of included studies reported significant improvements in sympt..
May 20 2025	Sanz et al., PLOS One, doi:10.1371/journal.pone.0323910	Hospitalised children with COVID-19 display an aberrant intestinal microbiota and a shift in faecal compounds related with the metabolism of vitamins and lipids
	Analysis of 16 children hospitalized with COVID-19 and 20 age-matched healthy controls showing altered gut microbiota and faecal metabolomic profiles in infected children. COVID-19 patients had higher abundance of opportunistic bacteria a..
May 13 2025	Mousavi et al., Frontiers in Pediatrics, doi:10.3389/fped.2025.1436633	Vitamin D status in children with mild, moderate, or severe confirmed COVID-19: systematic-review and meta-analysis
	Meta-analysis of 12 studies showing significantly lower vitamin D levels in COVID-19 patients compared to healthy controls. Children with moderate COVID-19 had 3.6 times higher odds of vitamin D deficiency compared to aymptomatic patients..
May 6 2025	Ito et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2025.05.007	Serum Vitamin D and the Risk of SARS-CoV-2 and Seasonal Influenza Infection During the Twindemic Period
	5% more cases (p=0.89). Survey of 1,434 hospital staff members showing no significant difference in COVID-19 or influenza cases based on vitamin D sufficiency.
Apr 30 2025	Tanriverdi et al., International Journal of Tokat Medical Sciences, 17:18-25	COVİD-19 Pnömonisi Gelişen Hastalarda Vitamin D Düzeylerinin Hastane Yatış Süresi ve Mortalite ile İlişkisinin Değerlendirilmesi: Retrospektif Analiz
	60% lower mortality (p=0.07). Retrospective 178 hospitalized COVID-19 pneumonia patients showing higher mortality with lower vitamin D levels.
Apr 25 2025	Maguire et al., Communications Medicine, doi:10.1038/s43856-025-00844-4	Dissecting clinical features of COVID-19 in a cohort of 21,312 acute care patients
	Retrospective 21,312 acute care COVID-19 patients in the USA showing that low albumin levels were one of the best predictors of disease severity, with hypoalbuminemia associated with higher rates of severe/critical disease trajectories an..
Apr 16 2025	Morello et al., Italian Journal of Pediatrics, doi:10.1186/s13052-025-01961-5	Role of nutrient supplements in children with post-COVID condition: a retrospective preliminary observation and narrative review
	Retrospective 1,243 children with COVID-19 showing lower risk of long COVID at 6 months when treated with a Multi-Element Product (MEP) containing antioxidants and anti-inflammatory compounds (magnesium 200 mg, quercetin 150 mg, curcumin ..
Apr 1 2025	Hossain et al., National Journal of Medical Research, doi:10.55489/njmr.150220251070	A Study on Serum Vitamin D3 Level in Patients with Covid-19: A Cross-Sectional Study in Kolkata
	58% lower severe cases (p=0.002). Analysis of 100 hospitalized COVID-19 patients in India showing strong association between vitamin D deficiency and COVID-19 severity.
Mar 25 2025	Gkioulekas et al., The Japanese Journal of Antibiotics, doi:10.11553/antibiotics.78.1_35	Critical appraisal of multidrug therapy in the ambulatory management of patients with COVID-19 and hypoxemia Part II: Causal inference using the Bradford Hill criteria
	Critical appraisal of three case series totaling 119 COVID-19 patients with hypoxemia treated with ivermectin-based multidrug protocols in the United States, Zimbabwe, and Nigeria, showing reduced hospitalization and mortality. Authors ap..
Mar 25 2025	Gkioulekas, Ph.D. et al., The Japanese Journal of Antibiotics, doi:10.11553/antibiotics.78.1_2	Critical appraisal of multidrug therapy in the ambulatory management of patients with COVID-19 and hypoxemia Part I. Evidence supporting the strength of association
	Critical appraisal of 119 COVID-19 hypoxemic patients treated with ivermectin-based multidrug protocols in the United States, Zimbabwe, and Nigeria, showing significant hospitalization rate reduction and mortality rate reduction compared ..
Mar 14 2025	Brandão et al., Frontiers in Nutrition, doi:10.3389/fnut.2025.1549747	Vaccination and food consumption: association with Post-Acute COVID-19 Syndrome in Brazilian adults (CUME Study)
	19% lower long COVID (p=0.04). Analysis of 2,065 Brazilian adults participating in the CUME study showing that higher intake of vitamin C, vitamin D, zinc, white meat, and vegetables were associated with lower risk of long COVID.
Mar 5 2025	Domènech-Montoliu et al., Tropical Medicine and Infectious Disease, doi:10.3390/tropicalmed10040098 (date from preprint)	Vitamin D Status and Incidence of SARS-CoV-2 Reinfections in the Borriana COVID-19 Cohort: A Population-Based Prospective Cohort Study
	38% fewer cases (p=0.02). Prospective cohort study of 378 confirmed SARS-CoV-2 cases in Spain showing increased risk of SARS-CoV-2 reinfection with insufficient vitamin D status.
Mar 4 2025	Kafeshani et al., Journal of Health System Research, doi:10.48305/jhsr.v21i1.1579	Investigating the Relationship between Food Intake and Severity of COVID-19 Disease: A Cross-Sectional Study
	Cross-sectional study of 3,018 hospitalized (moderate and severe) and 717 outpatient (mild) COVID-19 patients showing differences in nutritional intake associated with disease severity. Patients requiring hospitalization had significantly..
Mar 3 2025	Seifi Skishahr et al., Jentashapir Journal of Cellular and Molecular Biology, doi:10.5812/jjcmb-159606	Evaluation of Glutathione Redox Status and Inflammatory Markers in ICU Patients with Acute Respiratory Syndrome due to COVID-19
	Rerospective 16 COVID-19 ICU patients and 16 healthy controls, showing significantly lower vitamin D levels in COVID-19 patients.
Feb 20 2025	Hewison, M., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2025.106710	COVID-19 and our understanding of vitamin D and immune function
	Review of vitamin D's role in immune function with a focus on COVID-19. Author outlines how vitamin D influences both innate and adaptive immunity through multiple mechanisms that could impact viral infections including SARS-CoV-2. The re..
Feb 19 2025	Vasconcelos et al., Nutrition in Clinical Practice, doi:10.1002/ncp.11277	High-dose vitamin D supplementation in patients with severe acute respiratory syndrome coronavirus 2 pneumonia hospitalized in a polyvalent intensive care unit: A retrospective cohort study
	73% lower mortality (p=0.02). Retrospective ICU patients in Portugal, showing significantly lower mortality with vitamin D treatment.
Feb 14 2025	Perestiuk et al., Frontiers in Pediatrics, doi:10.3389/fped.2025.1507169	Vitamin D status in children with COVID-19: does it affect the development of long COVID and its symptoms?
	54% lower long COVID (p=0.03). Prospective study of 162 hospitalized children in Ukraine showing increased risk of developing long COVID in children with vitamin D deficiency/insufficiency, especially neurological and musculoskeletal symptoms.
Feb 6 2025	Wimalawansa, S., Nutrients, doi:10.3390/nu17030599	Vitamin D Deficiency Meets Hill’s Criteria for Causation in SARS-CoV-2 Susceptibility, Complications, and Mortality: A Systematic Review
	Systematic review examining the evidence for vitamin D deficiency as a causative factor in COVID-19 susceptibility, complications, and mortality, evaluated using Bradford Hill's criteria for causality. Author analyzed 294 studies, finding..
Feb 1 2025	Izadi et al., Iranian Journal Of Health Sciences, doi:10.32598/ijhs.13.1.1070.1	The Association Between Vitamin D Serum Level and Severity of COVID-19: A Cross-sectional Study
	Cross-sectional study of 121 COVID-19 patients showing higher vitamin D levels associated with lower risk of severe COVID-19.
Jan 31 2025	Najih et al., Cureus, doi:10.7759/cureus.78291	Impact of Vitamin D Levels on Clinical Outcomes in SARS-CoV-2 Infections
	53% fewer symptomatic cases (p=0.002). Cross-sectional study of 100 COVID-19 patients showing low vitamin D levels associated with increased symptom severity.
Jan 30 2025	Sümegi et al., Nutrients, doi:10.3390/nu17030507	Effect of Moderately High-Dose Vitamin D3 Supplementation on Mortality in Patients Hospitalized for COVID-19 Infection
	67% lower mortality (p=0.0002). Retrospective 148 hospitalized COVID-19 patients showing significantly lower mortality (67% reduction) with moderately high-dose vitamin D3 treatment (30,000 IU for 3 days or 12,000 IU for 7 days followed by 3,000 IU daily), regardless of..
Jan 20 2025	Knez et al., Frontiers in Immunology, doi:10.3389/fimmu.2024.1490478	TLR10 overexpression modulates immune response in A549 lung epithelial cells challenged with SARS-CoV-2 S and N proteins
	In vitro study showing that overexpression of TLR10 in A549 lung epithelial cells immunostimulated with SARS-CoV-2 S and N proteins mainly downregulated proinflammatory cytokines and interferons and affected gene expression in cocultured ..
Jan 16 2025	Sanduzzi Zamparelli et al., Life, doi:10.3390/life15010113	Immune-Boosting and Antiviral Effects of Antioxidants in COVID-19 Pneumonia: A Therapeutic Perspective
	Review of immune-boosting and antiviral effects of antioxidants in COVID-19 pneumonia. Authors provide an overview of the literature on the use of antioxidants, including vitamins, trace elements, ozone, glutathione, L-carnitine, melatoni..
Jan 16 2025	Atieh et al., Nutrients, doi:10.3390/nu17020304	Vitamins K2 and D3 Improve Long COVID, Fungal Translocation, and Inflammation: Randomized Controlled Trial
	RCT 151 long COVID outpatients showing improved long COVID Research Index, number of symptoms, inflammatory markers, and fungal translocation with vitamins D3 and K2 over 24 weeks. D3 2000IU daily and K2 240µg. Markers of inflammation (ox..
Jan 1 2025	Alzahrani, A., Octahedron Drug Research, doi:10.21608/odr.2024.308273.1043	A new investigation into the molecular mechanism of cholecalciferol towards reducing cytokines storm
	In silico study showing that cholecalciferol (vitamin D3) exhibits strong binding affinity to multiple cytokines involved in cytokine storm, with binding energies exceeding -6.5 kcal/mol. Molecular dynamics simulations revealed remarkable..
Dec 31 2024	Mohamed et al., The Medical Journal of Cairo University, doi:10.21608/mjcu.2024.411836	Nutritional Assessment of Critically Ill Children with COVID-19 Admitted to PICU
	45% lower mortality (p=0.19). Retrospective 60 hospitalized pediatric COVID-19 patients showing deficiencies in vitamin D, folic acid (B9), zinc, and selenium associated with higher mortality.
Dec 30 2024	Simón-Frapolli et al., Nutrients, doi:10.3390/nu17010110	Relationship Between Vitamin D Levels with In-Hospital Complications and Morphofunctional Recovery in a Cohort of Patients After Severe COVID-19 Across Different Obesity Phenotypes
	Prospective observational study of 94 postcritical COVID-19 patients showing that higher vitamin D levels were associated with fewer complications, shorter hospital and ICU stays, and improved morphofunctional recovery. Vitamin D deficien..
Dec 22 2024	You et al., Hemodialysis International, doi:10.1111/hdi.13194	Associations of vitamin D levels and clinical parameters with COVID‐19 infection, severity and mortality in hemodialysis patients: A cohort study
	82% lower mortality (p=0.15) and 96% lower severe cases (p=0.01). Retrospective 198 hemodialysis patients in China showing vitamin D deficiency associated with an increased risk of COVID-19 severity.
Feb 20 2025	Dinoi et al., Biomedicines, doi:10.3390/biomedicines13030535 (date from preprint)	Retrospective Clinical Investigation into the Association Between Abnormal Blood Clotting, Oral Anticoagulant Therapy, and Medium-Term Mortality in a Cohort of COVID-19 Patients
	48% lower mortality (p=0.0005). Retrospective 247 non-survivors and 247 matched survivors in hospitalized COVID-19 patients in Italy showing results for several treatments.
Dec 1 2024	Mogire, R., PLOS Global Public Health, doi:10.1371/journal.pgph.0004074 (date from preprint)	Early Pandemic Associations of Latitude, Sunshine Duration, and Vitamin D Status with COVID-19 Incidence and Fatalities: A Global Analysis of 187 Countries
	Analysis of 187 countries showing higher latitude and lower vitamin D levels associated with increased COVID-19 prevalence, mortality, and case fatality rates during the early months of the pandemic.
Nov 26 2024	Chen et al., Journal of Medical Virology, doi:10.1002/jmv.70085	In Vitro Characterization of Inhibition Function of Calcifediol to the Protease Activity of SARS-COV-2 PLpro
	In vitro study showing that calcifediol inhibits SARS-CoV-2 papain-like protease (PLpro) activity through targeted binding. Authors conducted a FRET-based screening experiment, supported by in vitro interaction studies, demonstrating calc..
Nov 25 2024	Chadda et al., Frontiers in Medicine, doi:10.3389/fmed.2024.1494129	Vitamin D deficiency and duration of COVID-19 symptoms in UK healthcare workers
	7% faster recovery (p=0.49) and 27% lower progression (p=0.01). Retrospective 392 healthcare workers in the UK showing vitamin D deficiency associated with a greater quantity of COVID-19 symptoms and longer durations of body aches and fatigue. Authors hypothesize that the anti-inflammatory properties ..
Nov 21 2024	Haque et al., Discover Molecules, doi:10.1007/s44345-024-00005-5	Exploring potential therapeutic candidates against COVID-19: a molecular docking study
	In silico study showing potential inhibition of SARS-CoV-2 proteins by various compounds including dactinomycin, itraconazole, ivermectin, vitamin D, quercetin, curcumin, montelukast, bromhexine, hesperidin, EGCG and raloxifene. Authors p..
Nov 18 2024	Pashaei et al., Journal of Comprehensive Pediatrics, doi:10.5812/jcp-149127	The Association Between COVID-19 Infection Severity and Micronutrient Deficiencies in Children
	12% lower severe cases (p=0.76). Analysis of 85 pediatric patients (33 healthy controls, 25 mild COVID-19, 27 severe COVID-19), showing significantly lower serum zinc levels in severe COVID-19 patients compared to healthy controls. Severe cases had higher prevalence of z..
Nov 11 2024	Fazli et al., Journal of Medical Bacteriology, 12:4	Possible Link between Gut Microbiota, Diet, and COVID-19 Infection
	Review of the relationship between gut microbiota, diet, and COVID-19 infection. Authors analyze how SARS-CoV-2 infection affects gut microbiota composition and how dietary factors may influence disease outcomes. Studies show COVID-19 pat..
Nov 6 2024	Mirkarimi et al., Health Science Reports, doi:10.1002/hsr2.70181	Clinical and Epidemiological Features of Pediatric COVID‐19: A Retrospective Study
	63% fewer moderate/severe cases (p<0.0001). Retrospective 600 hospitalized pediatric COVID-19 patients, showing vitamin D insufficiency/deficiency associated with COVID-19 severity.
Nov 5 2024	Sartini et al., Nutrients, doi:10.3390/nu16223794	The Effect of Vitamin D Supplementation Post COVID-19 Infection and Related Outcomes: A Systematic Review and Meta-Analysis
	Meta analysis of 29 studies showing significantly lower ICU admission and intubation rates with vitamin D treatment in COVID-19 patients. Mortality was significantly reduced in observational studies but without statistical significance in..
Nov 1 2024	Wang et al., Medicine, doi:10.1097/MD.0000000000040245	Vitamin D levels in children and adolescents are associated with coronavirus disease-2019 outcomes: A systematic review and meta-analysis
	Systematic review and meta-analysis of 9 studies with 1,262 children showing higher risk of COVID-19 infection and severe illness with vitamin D insufficiency.
Oct 31 2024	Wojciulik et al., Przeglad Epidemiologiczny, doi:10.32394/pe/194862	The impact of genetic polymorphism on course and severity of the SARS-CoV-2 infection and COVID-19 disease
	Review of genetic polymorphisms associated with the course and severity of SARS-CoV-2 infection and COVID-19 disease. Authors describe several genetic variants that influence susceptibility to severe COVID-19, including polymorphisms in A..
Oct 20 2024	Chan et al., Cureus, doi:10.7759/cureus.71952	Short-Term Outcomes in Patients With Coexistence of COVID-19 Infection and Vitamin D Deficiency: A Large Cohort Study
	6% lower mortality (p=0.42), 5% lower progression (p=0.02), and 1% lower hospitalization (p=0.8). PSM retrospective 68,814 COVID-19 patients showing vitamin D deficiency associated with significantly increased risk of requiring critical care services, and non-significant higher all-cause mortality. Mortality for COVID-19 was less like..
Oct 16 2024	Kurosaki et al., Scientific Reports, doi:10.1038/s41598-024-75338-9	SARS-CoV-2 infection causes a decline in renal megalin expression and affects vitamin D metabolism in the kidney of K18-hACE2 mice
	Mouse study showing that SARS-CoV-2 infection decreases renal megalin expression and affects vitamin D metabolism in K18-hACE2 mice. Authors found that infected mice experienced acute kidney injury, suppressed megalin protein levels in pr..
Oct 16 2024	Wimalawansa, S., Biology, doi:10.3390/biology13100831	Unveiling the Interplay—Vitamin D and ACE-2 Molecular Interactions in Mitigating Complications and Deaths from SARS-CoV-2
	Review of the interplay between vitamin D and angiotensin-converting enzyme-2 (ACE2) in mitigating complications and deaths from SARS-CoV-2. Author reports that over 300 clinical studies have shown that proper doses of vitamin D effective..
Oct 6 2024	Santa et al., Frontiers in Nutrition, doi:10.3389/fnut.2024.1465324	Comparative analysis of COVID-19 responses in Japan and Africa: diet, phytochemicals, vitamin D, and gut microbiota in reducing mortality—A systematic review and meta-analysis
	Comparative analysis of COVID-19 responses in Japan and Africa, focusing on diet, phytochemicals, vitamin D, and gut microbiota in reducing mortality. Authors conducted a systematic review and meta-analysis to investigate the unexpectedly..
Sep 26 2024	Korkmaz et al., Infectious Diseases and Clinical Microbiology, doi:10.36519/idcm.2024.324	A New Biomarker Copeptin in Determining Disease Severity in COVID-19
	Prospective study of 90 hospitalized COVID-19 patients showing that vitamin D levels were significantly lower in severe cases compared with mild/moderate cases. Hemoglobin and total protein were also lower in severe cases, while C-reactiv..
Sep 25 2024	Zhang et al., Frontiers in Nutrition, doi:10.3389/fnut.2024.1441847	The impact of supplementing vitamin D through different methods on the prognosis of COVID-19 patients: a systematic review and meta-analysis
	28% lower mortality (p=0.02), 22% lower ventilation (p=0.14), and 42% lower ICU admission (p=0.01). Systematic review and meta analysis of 21 studies with 4,553 COVID-19 patients showing significantly lower mortality and ICU admission rates with vitamin D supplementation. Improved results were seen with continuous dosing, total doses le..
Sep 24 2024	Grosman-Dziewiszek et al., Nutrients, doi:10.3390/nu16193225	Patterns of Dietary Supplement Use during the COVID-19 Pandemic in Poland: Focus on Vitamin D and Magnesium
	Survey of 926 Polish pharmacy patients showing a high prevalence of dietary supplemention during the COVID-19 pandemic, with vitamin D and magnesium being the most commonly used. Supplement use was significantly higher among women, those ..
Sep 18 2024	Kaushal, A., Journal of Translational Medicine, doi:10.1186/s12967-024-05587-9	Nutraceuticals and pharmacological to balance the transitional microbiome to extend immunity during COVID-19 and other viral infections
	Review of nutraceuticals and pharmacological interventions to balance the microbiome and boost immunity during COVID-19 and other viral infections. Authors propose that optimal usage of probiotics, dietary fibers, vitamins, minerals, omeg..
Sep 16 2024	Mu et al., Journal of Agriculture and Food Research, doi:10.1016/j.jafr.2024.101422	Anti-inflammatory and Nutritional Interventions Against SARS-CoV-2: A Comprehensive Review
	Review of anti-inflammatory and nutritional interventions against SARS-CoV-2. Authors emphasize the importance of a healthy immune response in reducing the severity of COVID-19, especially in high-risk groups like the elderly and those wi..
Sep 16 2024	García-Zendejas et al., Cirugía y Cirujanos, doi:10.24875/CIRU.23000514	Asociación de los niveles de vitamina D y magnesio con la gravedad y la mortalidad en pacientes con COVID-19
	65% lower mortality (p=0.18), 64% lower ICU admission (p=0.15), 84% lower hospitalization (p=0.02), and 58% fewer cases (p=0.26). Case-control study with 54 hospitalized patients, 27 COVID-19 positive and 27 negative, showing higher risk of cases, hospitalization, ICU admission, and death with vitamin D deficiency, with statistical significance only for hospitalizat..
Sep 13 2024	Rachman et al., Medicine, doi:10.1097/MD.0000000000039252	Adequate serum 25-hydroxy-vitamin D levels are correlated with low anti-PF4 levels in mild COVID-19 Patients: An observational study
	52% lower severe cases (p=0.37). Retrospective 160 COVID-19 patients in Indonesia showing a significant negative correlation between vitamin D levels and anti-PF4 antibodies in mild COVID-19 patients. Severe COVID-19 patients were more likely to have vitamin D deficiency..
Sep 3 2024	Kow et al., Inflammopharmacology, doi:10.1007/s10787-024-01564-2	The impact of vitamin D administration on mortality in COVID-19 patients: a systematic review and meta-analysis of randomized controlled trials
	28% lower mortality (p=0.04). Systematic review and meta analysis of 19 RCTs with 2,495 patients, showing significantly lower mortality with vitamin D treatment.
Sep 3 2024	Karcıoğlu Batur et al., Diagnostics, doi:10.3390/diagnostics14171941	Investigation of the Relationship between Vitamin D Deficiency and Vitamin D-Binding Protein Polymorphisms in Severe COVID-19 Patients
	Genetic association study of 56 adult COVID-19 patients showing an association between vitamin D deficiency, vitamin D-binding protein (VDBP) gene polymorphisms rs7041 and rs4588, and the severity of COVID-19, including the need for ICU..
Sep 2 2024	Secerlı et al., Toxicology Research, doi:10.1093/toxres/tfae177	Effects of Immunotoxicity biomarkers, essential elements and vitamin D levels on the severity levels of COVID-19 disease in Turkey
	Analysis of 52 COVID-19 patients and 20 healthy controls, showing lower vitamin D, zinc, and selenium levels associated with COVID-19 progression.
Aug 27 2024	Sajinadiyasa et al., International Journal of Advances in Medicine, doi:10.18203/2349-3933.ijam20242306	Correlations between level of vitamin D serum and disease severity COVID-19
	Analysis of 68 COVID-19 patients in Indonesia showing higher vitamin D levels associated with lower COVID-19 severity.
Aug 16 2024	Hammam et al., The Egyptian Journal of Internal Medicine, doi:10.1186/s43162-024-00351-3	Relation between vitamin D and COVID-19 in Egyptian patients
	52% lower severe cases (p=0.02) and 96% fewer cases (p<0.0001). Retrospective case-control study of 90 COVID-19 patients and 90 matched controls showing significantly lower vitamin D levels in COVID-19 patients compared to controls. Lower vitamin D levels were associated with more severe COVID-19, res..
Aug 14 2024	Wang et al., Nutrition Journal, doi:10.1186/s12937-024-00990-w	Optimal methods of vitamin D supplementation to prevent acute respiratory infections: a systematic review, dose–response and pairwise meta-analysis of randomized controlled trials
	Systematic review and meta-analysis of 43 RCTs involving 49,320 participants showing lower risk of acute respiratory infections (ARIs) with vitamin D treatment for trials using daily doses of 400-1200 IU/day. Trials shorter than four mont..
Jul 30 2024	Değirmenci et al., Journal of Controversies in Obstetrics & Gynecology and Pediatrics, doi:10.51271/JCOGP-0035	Is vitamin D level important in pregnant women with COVID-19?
	51% lower ICU admission (p=0.27), 36% lower progression (p=0.53), and 17% shorter hospitalization (p=0.48). Retrospective 125 pregnant women hospitalized with COVID-19 in Turkey, showing no significant differences with vitamin D deficiency.
Jul 28 2024	Charoenporn et al., Psychiatry and Clinical Neurosciences, doi:10.1111/pcn.13716	Effects of an 8‐week high‐dose vitamin D supplementation on fatigue and neuropsychiatric manifestations in post‐COVID syndrome: A randomized controlled trial
	RCT 80 long COVID patients showing benefits with high-dose vitamin D treatment. Participants received 60,000 IU vitamin D weekly or placebo for 8 weeks. The vitamin D group showed significant improvements in fatigue (CFQ score), anxiety..
Jul 17 2024	Wimalawansa, S., Heliyon, doi:10.1016/j.heliyon.2024.e34691	Unlocking Insights: Navigating COVID-19 Challenges and Emulating Future Pandemic Resilience Strategies with Strengthening Natural Immunity
	Review showing reduced efficacy of interventions with new variants and suggesting that regulators and health organizations should consider approval and strategic use of cost-effective adjunct therapies such as vitamin D and ivermectin tha..
Jul 16 2024	Imran et al., Clinical Nutrition Open Science, doi:10.1016/j.nutos.2024.07.004	Therapeutic Role of Vitamin D in COVID-19 Patients
	Review of vitamin D for COVID-19. Low vitamin D levels have been associated with increased susceptibility to and severity of COVID-19. Vitamin D plays an essential role in modulating the immune response and reducing inflammation, with pro..
Jul 15 2024	Abdelhai et al., The Egyptian Journal of Hospital Medicine, doi:10.21608/EJHM.2024.368093	Impact of Rapid Correction of Vitamin D Deficiency on Patients with COVID-19 Disease: A Randomized-Controlled Trial
	83% lower mortality (p<0.0001), 45% shorter hospitalization (p<0.0001), and 74% improved viral clearance (p<0.0001). RCT 250 hospitalized COVID-19 patients showing significant clinical improvement with high-dose intramuscular vitamin D3 treatment. Patients receiving 200,000 IU cholecalciferol daily for 4 days had increased vitamin D levels, reduced infl..
Jul 15 2024	Budelon Gonçalves et al., International Journal of Molecular Sciences, doi:10.3390/ijms25147749	Nutritional and Inflammatory Markers Associated with SARS-CoV-2 Infection in the Elderly
	Retrospective 43 elderly hospitalized COVID-19 patients in Brazil showing no significant association between vitamin D levels and clinical outcomes. Patients with vitamin D deficiency showed increased inflammatory markers. Data in this st..
Jul 8 2024	Pietzner et al., Communications Medicine, doi:10.1038/s43856-024-00506-x	Complex patterns of multimorbidity associated with severe COVID-19 and long COVID
	55% lower mortality (p<0.0001), 53% lower hospitalization (p<0.0001), 25% lower ARDS (p=0.05), and 56% lower long COVID (p<0.0001). Retrospective 502,460 UK Biobank participants identifying many pre-existing conditions associated with increased risk of severe COVID-19 and long COVID, including vitamin D deficiency.
Jul 5 2024	AlKhuzaie et al., Problems of Virology, doi:10.36233/0507-4088-236	Electrolytes, Zinc and Vitamin D3 in COVID-19 Patients with Cardiovascular Complications
	Retrospective 142 COVID-19 patients and 50 controls showing significantly lower levels of zinc, vitamin D, calcium, potassium, and sodium in COVID-19 patients compared to controls. Lower levels of zinc, vitamin D, calcium, and sodium were..
Jun 25 2024	Dip et al., International Journal of Advances in Medicine, doi:10.18203/2349-3933.ijam20241623	Vitamin D status and its association with the severity of COVID-19 among hospitalized patients
	88% lower severe cases (p=0.003). Cross-sectional study of 103 hospitalized COVID-19 patients in Bangladesh showing that vitamin D deficiency was independently associated with greater disease severity.
Jun 20 2024	Božić et al., Acta Facultatis Medicae Naissensis, doi:10.5937/afmnai41-42961	The role of serum vitamin D concentrations in predicting COVID-19 course and outcome
	53% lower mortality (p=0.007) and 30% lower ICU admission (p=0.21). Prospective study of 329 hospitalized COVID-19 patients in Serbia showing vitamin D deficiency associated with significantly higher mortality.
Jun 12 2024	Sanz et al., Hipertensión y Riesgo Vascular, doi:10.1016/j.hipert.2024.04.002	Vitamin D3 supplementation in COVID-19 patients with cardiovascular disease and gut dysbiosis
	83% lower ventilation (p=0.06) and 60% lower ICU admission (p=0.36). Small RCT 22 hospitalized COVID-19 patients with cardiovascular disease in Argentina showing lower mortality, ventilation, and ICU admission with vitamin D treatment, without statistical significance. Treatment was associated with lower l..
Jun 11 2024	Cardoso et al., medRxiv, doi:10.1101/2024.06.10.24308690	Vitamin D levels and COVID-19 severe pneumonia: a prospective case-control study
	67% lower progression (p<0.0001). Prospective case-control study of 614 patients in Brazil showing lower vitamin D levels associated with increased risk of severe COVID-19 pneumonia.
Jun 9 2024	Singhsakul et al., Journal of Southeast Asian Medical Research, doi:10.55374/jseamed.v8.202	Association of vitamin D level and severity of COVID-19 disease
	51% lower severe cases (p=0.02) and 67% fewer moderate/severe cases (p=0.34). Retrospective 97 hospitalized COVID-19 patients in Thailand showing vitamin D deficiency associated with higher risk of severe illness.
Jun 2 2024	Noraldinvand et al., Journal of Medical Bacteriology, doi:10.18502/jmb.v12i2.15620	Determination of Serum Vitamin D Levels in Patients with COVID-19
	Retrospective 100 suspected COVID-19 patients showing significantly lower vitamin D levels in COVID-19 positive patients compared to negative patients.
Jun 1 2024	Morad et al., QJM: An International Journal of Medicine, doi:10.1093/qjmed/hcae070.291	Measurement of Vitamin D Level among Covid-19 Patients and its Correlation with Severity of the Disease
	Retrospective 80 COVID-19 patients showing that patients with the most severe chest CT findings had the lowest average vitamin D levels. Patients with lower vitamin D levels had significantly higher levels of inflammatory markers (CRP and..
May 27 2024	Yang et al., Frontiers in Pharmacology, doi:10.3389/fphar.2024.1367686	Therapeutic effects of vitamin D supplementation on COVID-19 aggravation: a systematic review and meta-analysis of randomized controlled trials
	Meta analysis of 19 RCTs with 2,435 total participants showing significantly lower ICU admission and mechanical ventilation with vitamin D treatment. Results were better for moderate to severe COVID-19 patients, and with multiple dose ver..
May 15 2024	Wang et al., Cell Biochemistry and Function, doi:10.1002/cbf.4039	1,25‐Dihydroxyvitamin D3 attenuates platelet aggregation potentiated by SARS‐CoV‐2 spike protein via inhibiting integrin αIIbβ3 outside‐in signaling
	In vitro study showing that calcitriol minimizes platelet aggregation mediated by SARS-CoV-2 spike protein via inhibiting integrin αIIbβ3 outside-in signaling. Authors find that calcitriol reduces platelet aggregation and Src-mediated sig..
May 10 2024	Hazan et al., Cureus, doi:10.7759/cureus.60038	Bifidobacterium Against COVID-19: A Mother and Her Newborn’s Gut Microbiome
	Case report of a mother and her newborn infected with COVID-19 within two weeks of the baby's birth. Authors propose that the disease course was altered by maternal supplementation of vitamins C and D and zinc starting after exposure on d..
May 9 2024	Dong et al., Frontiers in Pharmacology, doi:10.3389/fphar.2024.1388348	Vitamin D level in COVID-19 patients has positive correlations with autophagy and negative correlations with disease severity
	Retrospective 52 COVID-19 patients showing that patients with severe/critical disease had lower levels of vitamin D and autophagy markers ATG7 and BECN1 compared to those with mild or moderate disease. Vitamin D levels had a significant n..
May 7 2024	Sobczak et al., Nutrients, doi:10.3390/nu16101402	Effect of Vitamin D3 Supplementation on Severe COVID-19: A Meta-Analysis of Randomized Clinical Trials
	44% lower mortality (p=0.02), 27% lower ICU admission (p=0.02), and 21% lower need for oxygen therapy (p=0.07). Meta analysis of 13 RCTs for severe COVID-19 showing lower ICU admission and lower COVID-19 mortality with vitamin D treatment. Other outcomes show lower risk with treatment but without statistical significance. Authors conclude that it i..
May 3 2024	Mohammadifard et al., Scientific Reports, doi:10.1038/s41598-024-57424-0	Comparing vitamin D receptor gene polymorphisms in rs11568820, rs7970314, rs4334089 between COVID-19 patients with mild and severe symptoms: a case control study
	Case control study of 176 COVID-19 patients showing the TT genotype of the rs11568820 vitamin D receptor (VDR) polymorphism was associated with a lower risk of severe COVID-19 requiring hospitalization. No significant differences were fou..
Apr 30 2024	Milan et al., Acta Medica Philippina, doi:10.47895/amp.v58i7.8392	Factors Associated with Adverse Outcomes among SARS-CoV-2 Positive Children in a Tertiary Government COVID-19 Referral Hospital in the Philippines
	47% lower mortality (p=0.18), 21% lower ventilation (p=0.53), and 16% lower ICU admission (p=0.69). Retrospective 180 hospitalized pediatric COVID-19 patients in the Philippines showing lower mortality with vitamin D and zinc, and higher mortality with remdesivir, all without statistical significance. Remdesivir was given to few patient..
Apr 28 2024	Ochoa-Ramírez et al., International Journal of Immunogenetics, doi:10.1111/iji.12674	Vitamin D receptor gene polymorphisms role in COVID‐19 severity: Results of a Mexican patients’ cohort
	Retrospective 292 COVID-19 patients finding that haplotype TC of the FokI and TaqI vitamin D receptor (VDR) gene polymorphisms was associated with an increased risk of critical COVID-19.
Apr 27 2024	Autier et al., medRxiv, doi:10.1101/2024.04.26.24306354	Vitamin D, acute respiratory infections, and Covid-19: the curse of small-size randomised trials. A critical review with meta-analysis of randomised trials
	Unregistered meta analysis cherry-picking the ICU outcome and including 9 late treatment RCTs with ICU outcomes for vitamin D. It's unclear why ICU risk would be used when there are more studies reporting mortality which is also less subj..
Apr 24 2024	Jamilian et al., Public Health Nutrition, doi:10.1017/S1368980024000934	The role of vitamin D in outcomes of critical care in COVID-19 patients: Evidence from an umbrella meta-analysis of interventional and observational studies
	58% lower mortality (p=0.05). Umbrella meta analysis of 13 meta analyses showing significantly lower mortality with vitamin D supplementation, and significantly higher mortality, infection risk, and severity with vitamin D deficiency in COVID-19 patients. Lower vitami..
Apr 5 2024	Pavlyshyn et al., Неонатологія, хірургія та перинатальна медицина, doi:10.24061/2413-4260.XIV.1.51.2024.6	Micronutrient status (vitamins A and D) and its effect on the severity of the course of COVID-19 in children
	60% lower severe cases (p=0.13) and 89% fewer cases (p=0.13). Retrospective 112 pediatric COVID-19 patients and 23 healthy controls showing lower levels of vitamins A and D associated with more severe disease. Patients with moderate and severe COVID-19 had significantly lower vitamin A, vitamin D, a..
Mar 29 2024	Begum et al., Sudan Journal of Medical Sciences, doi:10.18502/sjms.v19i1.15776	The Role of Vitamin D in COVID-19 Survival and Prevention: A Meta-analysis
	57% lower mortality (p=0.0002) and 48% fewer cases (p=0.05). Meta analysis of 16 studies including over 5.9 million patients showing significantly lower mortality and cases with vitamin D treatment.
Mar 28 2024	Arambepola et al., Research Square, doi:10.21203/rs.3.rs-3964082/v1	The role of vitamin D as a preventive strategy in COVID-19 infections: evidence from South Asia
	47% fewer cases (p=0.27). Case-control study of 104 hospitalized COVID-19 patients and 104 healthy controls in Sri Lanka, showing significantly lower serum vitamin D levels in cases compared to controls, and in moderate/severe cases compared to mild cases. There w..
Mar 27 2024	Zhang et al., Heliyon, doi:10.1016/j.heliyon.2024.e28629	The close association of micronutrients with COVID-19
	Case-control study with 149 healthy controls and 214 COVID-19 patients in China, showing significantly lower serum vitamin D levels in COVID-19 patients. Vitamin D was found to be an independent risk factor for COVID-19. A logistic regres..
Mar 24 2024	Mosadegh et al., AMB Express, doi:10.1186/s13568-024-01690-8	NBS superfood: a promising adjunctive therapy in critically ill ICU patients with omicron variant of COVID-19
	RCT 400 critically ill ICU patients with omicron-related ARDS showing significantly reduced mortality and inflammatory markers with a nutritional supplement containing vitamins A, B1-B3, B5, B6, B9, C, D, K, and zinc, potassium, manganese..
Mar 15 2024	Alcalá-Santiago et al., The 14th European Nutrition Conference FENS 2023, doi:10.3390/proceedings2023091415	Disentangling the Immunomodulatory Effects of Vitamin D on the SARS-CoV-2 Virus by In Vitro Approaches
	In vitro study showing that vitamin D inhibits inflammatory cytokine production in THP-1 cells stimulated with the SARS-CoV-2 spike protein. Authors used vitamin D at doses of 10 and 25 nM to treat THP-1 cells, a human monocytic cell line..
Mar 13 2024	Arboleda et al., Behavioural Public Policy, doi:10.1017/bpp.2024.11	EAST framework to promote adherence to nutritional supplementation: a strategy to mitigate COVID-19 within health workers
	36% fewer cases (p=0.03). Prospective study of 1,063 health workers in Colombia showing lower COVID-19 infection rates with adherence to a vitamin D and C supplementation plan, however very limited baseline information is provided for the adherent vs. non-adherent..
Mar 8 2024	Talebzadeh et al., Frontiers in Cellular and Infection Microbiology, doi:10.3389/fcimb.2024.1360075	The effect of vitamin D deficiency on platelet parameters in patients with COVID-19
	Retrospective study of 707 COVID-19 patients showing higher platelet count and mean platelet volume (MPV) in patients with vitamin D deficiency compared to those without deficiency and healthy controls. There was a significant negative co..
Mar 4 2024	Guðnadóttir et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2024.02.023	High risk of malnutrition among hospitalised coronavirus disease 2019 (COVID-19) patients is associated with mortality and other clinical outcomes
	54% lower mortality (p=0.15), 8% lower ventilation (p=0.87), and 28% lower ICU admission (p=0.43). Retrospective 273 hospitalized COVID-19 patients in Iceland showing high risk of malnutrition associated with ICU admission, mechanical ventilation, and mortality. Mortality was higher with vitamin D insufficiency, but this result was not..
Mar 2 2024	Tentolouris et al., Nutrients, doi:10.3390/nu16050727	The Association of Vitamin D Receptor Polymorphisms with COVID-19 Severity
	Case-control study of 137 COVID-19 patients and 72 controls in Greece showing an association between the TaqI vitamin D receptor polymorphism and increased risk of severe COVID-19, independent of potential confounders such as age, sex, an..
Mar 2 2024	Grant, W., Advances in Food and Nutrition Research, doi:10.1016/bs.afnr.2023.12.007	Vitamin D and viral infections: Infectious diseases, autoimmune diseases, and cancers
	Review of vitamin D and solar ultraviolet radiation-B (UVB) for reducing the risk of diseases related to viruses including certain respiratory tract diseases, autoimmune diseases, and several types of cancer. Author notes that vitamin D p..
Mar 1 2024	Vu et al., Emerging Infectious Diseases, doi:10.3201/eid3003.231194	Estimates of Incidence and Predictors of Fatiguing Illness after SARS-CoV-2 Infection
	Retrospective 4,589 COVID-19 patients and 9,022 matched controls showing that COVID-19 patients had a significantly higher risk of developing fatigue and chronic fatigue. Among COVID-19 patients, nutritional deficiency (including vitamin ..
Feb 28 2024	Sartini et al., Nutrients, doi:10.3390/nu16050679	Preventive Vitamin D Supplementation and Risk for COVID-19 Infection: A Systematic Review and Meta-Analysis
	Systematic review and meta analysis of 7 RCTs and 12 observational studies including over 1.2 million participants showing vitamin D prophylaxis associated with lower COVID-19 cases and lower ICU admission.
Feb 22 2024	Robak et al., Nutrients, doi:10.3390/nu16050598	The Distinct Regulation of the Vitamin D and Aryl Hydrocarbon Receptors in COVID-19
	Observational study of 240 COVID-19 patients showing vitamin D receptor (VDR) expression significantly upregulated in mild cases compared to controls, but impaired upregulation in critically ill patients. Patients who died had profound do..
Feb 3 2024	Regina da Silva Correa da Ronda et al., Gene, doi:10.1016/j.gene.2024.148236	Single-Nucleotide Polymorphisms Related to Vitamin D Metabolism and Severity or Mortality of COVID-19: A Systematic Review and Meta-analysis
	Systematic review and meta analysis of 12 studies examining associations between 31 single-nucleotide polymorphisms (SNPs) related to four vitamin D metabolism genes (VDR, GC, DHCR7, CYP2R1) and COVID-19 severity or mortality. Meta-analys..
Jan 31 2024	Węgrzynek-Gallina et al., Health Problems of Civilization, doi:10.5114/hpc.2023.133494	Profile of patients diagnosed with COVID-19 infection: a single-center retrospective study
	33% shorter hospitalization (p=0.001). Retrospective 232 hospitalized COVID-19 patients in Poland showing vitamin D deficiency associated with longer hospitalization.
Jan 29 2024	Rozemeijer et al., Nutrients, doi:10.3390/nu16030385	Micronutrient Status of Critically Ill Patients with COVID-19 Pneumonia
	Prospective pilot study of 20 critically ill COVID-19 ICU patients showing high deficiency rates of 50-100% for vitamins A, B6, and D; zinc; and selenium at admission. Deficiencies of vitamins B6 and D, and low iron status, persisted afte..
Jan 24 2024	Comunale et al., Vaccines, doi:10.3390/vaccines12020121	Vitamin D Supplementation and Prior Oral Poliovirus Vaccination Decrease Odds of COVID-19 Outcomes among Adults Recently Inoculated with Inactivated Poliovirus Vaccine
	91% fewer symptomatic cases (p=0.0006) and 88% fewer cases (p=0.001). Retrospective 282 adults recently vaccinated against poliovirus showing vitamin D supplementation associated with lower COVID-19 PCR+ cases, lower symptomatic cases, and shorter duration of symptoms.
Jan 23 2024	Fincham et al., BMC Medical Research Methodology, doi:10.1186/s12874-023-02110-4	Exploring trial publication and research waste in COVID-19 randomised trials of hydroxychloroquine, corticosteroids, and vitamin D: a meta-epidemiological cohort study
	Analysis of 357 HCQ, vitamin D, and corticosteroid COVID-19 RCTs registered before the end of 2021, showing that 70% had not published results as of October 2022. 70% of HCQ, 65% of vitamin D, and 72% of corticosteroid trials had not publ..
Jan 2 2024	Choi et al., Journal of Korean Medical Science, doi:10.3346/jkms.2024.39.e23	Prognostic Factors for Predicting Post-COVID-19 Condition in Patients With COVID-19 in an Outpatient Setting
	49% improved recovery (p=0.002), 68% lower long COVID (p=0.001), and 26% lower hospitalization (p=0.48). Retrospective 257 outpatients with mild COVID-19 in South Korea showing vitamin D deficiency (<20 ng/mL) associated with post-COVID condition and longer symptom duration.
Dec 30 2023	Efe Iris et al., Jundishapur Journal of Microbiology, doi:10.5812/jjm-140726	Vitamin D Deficiency and Receptor Polymorphisms as Risk Factors for COVID-19
	59% fewer cases (p<0.0001). Retrospective study of 100 COVID-19 positive hospitalized patients and 100 preoperative COVID-19 negative controls in Turkey, showing lower vitamin D levels associated with COVID-19. There was no significant association found for VDR gene..
Dec 25 2023	Polonowita et al., European Journal of Biomedical and Pharmaceutical sciences, doi:10.5281/zenodo.10435649	Molecular Quantum and Logic Process of Consciousness—Vitamin D Big-Data in COVID-19—A Case for Incorporating Machine Learning In Medicine
	Review of the integration of vitamin D data into machine learning for COVID-19-related healthcare decision-making. Authors highlight the role of vitamin D deficiency in increasing vulnerability to SARS-CoV-2 and argue that integrating vit..
Dec 19 2023	Wu et al., European Journal of Nutrition, doi:10.1007/s00394-023-03298-3	Association between vitamin D deficiency and post-acute outcomes of SARS-CoV-2 infection
	43% lower mortality (p=0.005), 19% lower hospitalization (p=0.0002), 10% lower progression (p=0.03), and 2% higher long COVID (p=0.93). TriNetX PSM retrospective 42,674 COVID-19 outpatients, showing higher mortality and hospitalization with vitamin D deficiency.
Dec 15 2023	Campolina-Silva et al., Viruses, doi:10.3390/v15122434	Dietary Vitamin D Mitigates Coronavirus-Induced Lung Inflammation and Damage in Mice
	Mouse study showing that vitamin D supplementation mitigates lung inflammation, damage, and lethality induced by the murine coronavirus MHV-3, which serves as a model for studying COVID-19 pathogenesis. Mice fed a vitamin D-rich diet exhi..
Dec 14 2023	Ren et al., Heliyon, doi:10.1016/j.heliyon.2023.e23662	Association of genetic polymorphisms with COVID-19 infection and outcomes: An updated meta-analysis based on 62 studies
	Meta-analysis of 62 studies with 19,600 COVID-19 cases showing certain genetic polymorphisms associated with COVID-19 infection risk, severity, and mortality. Specifically, the ACE I/D polymorphism was associated with lower COVID-19 infec..
Dec 11 2023	Morales-Bayuelo et al., F1000Research, doi:10.12688/f1000research.123550.3	New findings on ligand series used as SARS-CoV-2 virus inhibitors within the frameworks of molecular docking, molecular quantum similarity and chemical reactivity indices
	In silico analysis showing that cholecalciferol (vitamin D3) binds to the SARS-CoV-2 RNA-dependent RNA polymerase active site. Favorable stabilizing interactions were predicted, including hydrogen bonding with residues serine 759, glutami..
Dec 8 2023	Arian et al., PLOS ONE, doi:10.1371/journal.pone.0294899	Accuracy of artificial intelligence CT quantification in predicting COVID-19 subjects’ prognosis
	Retrospective 90 hospitalized COVID-19 patients in Iran showing lower vitamin D levels in critical vs. non-critical patients (20 vs. 26, p = 0.18).
Dec 8 2023	Triwongwaranat et al., Medicine, doi:10.1097/MD.0000000000036539	Characteristics of hair loss in COVID-19 patients in Thailand
	Retrospective 43 patients with abrupt onset hair loss within 4 months of COVID-19, noting that all 10 with data had low vitamin D levels.
Nov 26 2023	Renieris et al., Journal of Innate Immunity, doi:10.1159/000535302	Association of Vitamin D with severity and outcome of COVID-19: Clinical and Experimental Evidence
	52% lower mortality (p=0.04). Retrospective 190 hospitalized COVID-19 patients showing vitamin D deficiency associated with increased disease severity and mortality. Authors also report on mouse experiments that show vitamin D reduced lung inflammation and downregulat..
Nov 23 2023	Hu et al., Frontiers in Medicine, doi:10.3389/fmed.2023.1271060	Vitamin D supplementation is beneficial in improving the prognosis of patients with acute respiratory failure in the intensive care unit: a retrospective study based on the MIMIC-IV database
	40% lower mortality (p<0.0001). Retrospective 7,994 ICU patients with acute respiratory failure (not COVID-19 specific) in the USA showing significantly lower mortality with vitamin D supplementation.
Nov 15 2023	Moatasim et al., Microorganisms, doi:10.3390/microorganisms11112777	Potent Antiviral Activity of Vitamin B12 against Severe Acute Respiratory Syndrome Coronavirus 2, Middle East Respiratory Syndrome Coronavirus, and Human Coronavirus 229E
	In vitro and in silico analysis finding that methylcobalamin, hydroxocobalamin, and cyanocobalamin forms of vitamin B12 showed broad-spectrum inhibition against SARS-CoV-2, MERS-CoV, and HCoV-229E. Methylcobalamin had the highest activity..
Nov 13 2023	Gomaa et al., Inflammopharmacology, doi:10.1007/s10787-023-01383-x	Pharmacological evaluation of vitamin D in COVID-19 and long COVID-19: recent studies confirm clinical validation and highlight metformin to improve VDR sensitivity and efficacy
	Review of 58 studies with 14,071,273 patients showing a beneficial effect of vitamin D supplementation in COVID-19 and long COVID. 49 studies (86%) with 14,029,411 patients (99.7%) found vitamin D effective, including 12 meta-analyses. Ob..
Nov 7 2023	Akbar et al., Nutrients, doi:10.3390/nu16071037	The Association between Lifestyle Factors and COVID-19: Findings from Qatar Biobank
	19% fewer cases (p=0.02). Retrospective 10,000 adults in Qatar, showing lower risk of COVID-19 cases with vitamin D supplementation. Authors do not analyze COVID-19 severity.
Nov 7 2023	Vargas-Castro et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2024.106625 (date from preprint)	Calcitriol prevents SARS-CoV spike-induced inflammation in human trophoblasts through downregulating ACE2 and TMPRSS2 expression
	In vitro study showing that calcitriol prevents SARS-CoV-2 spike-induced inflammation in human trophoblasts through downregulation of ACE2 and TMPRSS2. Authors demonstrated that calcitriol significantly reduced expression of ACE2, TMPRSS2..
Oct 13 2023	Saheb Sharif-Askari et al., Scientific Reports, doi:10.1038/s41598-023-43675-w	Increased blood immune regulatory cells in severe COVID-19 with autoantibodies to type I interferons
	Cytometric analysis of the blood of 62 COVID-19 patients. Patients with severe COVID-19 had higher levels of regulatory T cells (Tregs) and regulatory B cells (Bregs) compared to patients with mild disease. Tregs and Bregs help control in..
Oct 4 2023	Abbasi et al., International Journal of Medical Laboratory, doi:10.18502/ijml.v10i3.13746	The Effects of Vitamin D3 and N-Acetylcysteine Administration in Patients with COVID-19 Hospitalization in the Iranian Population
	RCT 100 hospitalized patients reporting shorter hospitalization with vitamin D + N-acetylcysteine. However, day 28 SaO₂ is not consistent with the reported recovery values. For three arms the day 28 values are worse than the baseline valu..
Sep 22 2023	Seely et al., BMJ Open, doi:10.1136/bmjopen-2023-073761	Dietary supplements to reduce symptom severity and duration in people with SARS-CoV-2: a double-blind randomised controlled trial
	14% improved recovery (p=0.41). Early terminated low-risk population (no hospitalization) very late treatment (mean 8 days) RCT with 44 patients treated with vitamin C, D, K, and zinc, and 46 control patients, showing no significant differences. Authors acknowledge that..
Sep 20 2023	Meng et al., Clinical Nutrition, doi:10.1016/j.clnu.2023.09.008	The role of vitamin D in the prevention and treatment of SARS-CoV-2 infection: A meta-analysis of randomized controlled trials
	19% lower mortality (p=0.13), 42% lower ventilation (p=0.005), 37% lower ICU admission (p=0.01), and 69% fewer cases (p=0.12). Meta analysis of 25 RCTs showing lower mortality, ventilation, and ICU admission with vitamin D treatment. Results were better for multiple dose vs. single dose trials. For mortality, the results were statistically significant only for mu..
Sep 15 2023	Athanassiou et al., Life, doi:10.3390/life14020210 (date from preprint)	Vitamin D Levels as a Marker of Severe SARS-CoV-2 Infection
	48% lower mortality (p=0.39). Retrospective 88 hospitalized COVID-19 patients and matched controls, showing significantly lower vitamin D levels for COVID-19 patients, and higher mortality for COVID-19 patients with deficiency of insufficiency in unadjusted results, w..
Sep 13 2023	Qiu et al., Virology Journal, doi:10.1186/s12985-023-02165-1	Vitamin D status in hospitalized COVID‑19 patients is associated with disease severity and IL-5 production
	Retrospective 399 hospitalized patients in China, showing that lower vitamin D levels and higher IL-5 levels were independent risk factors for COVID-19 severity.
Sep 1 2023	Konikowska et al., Frontiers in Immunology, doi:10.3389/fimmu.2023.1231813	Association of serum vitamin D concentration with the final course of hospitalization in patients with COVID-19
	Retrospective 474 hospitalized COVID-19 patients in Poland, showing lower vitamin D levels associated with mortality.
Sep 1 2023	Ogasawara et al., Clinical Nutrition, doi:10.1016/j.clnu.2023.08.021	The effect of 1-hydroxy-vitamin D treatment in hospitalized patients with COVID-19: A retrospective study
	78% lower progression (p=0.05) and 75% lower need for oxygen therapy (p=0.09). PSM retrospective 312 hospitalized patients in Japan, showing lower progression with vitamin D (alfacalcidol) treatment, statistically significant via KM log-rank.
Aug 25 2023	Mbata et al., Journal of Clinical Medicine, doi:10.3390/jcm12175520	Is Serum 25-Hydroxyvitamin D Level Associated with Severity of COVID-19? A Retrospective Study
	Retrospective 763 hospitalized COVID-19 patients showing no significant difference in outcomes based on serum levels. Unadjusted results show non-significantly lower risk of critical severity, death, and complications with vitamin D suffi..
Aug 24 2023	Bogomaz et al., Canadian Journal of Respiratory Therapy, doi:10.29390/001c.87408	Vitamin D as a predictor of negative outcomes in hospitalized COVID-19 patients: An observational study
	70% lower mortality (p=0.24), 75% lower ventilation (p=0.23), 62% lower progression (p=0.3), and 27% lower need for oxygen therapy (p=0.24). Retrospective 70 hospitalized COVID-19 patients in Iran, showing higher mortality, ventilation, and need for respiratory support with low vitamin D levels, all without statistical significance. Adjusted results are provided only for respi..
Aug 14 2023	Al Sulaiman et al., Frontiers in Medicine, doi:10.3389/fmed.2023.1237903	Survival implications vs. complications: unraveling the impact of vitamin D adjunctive use in critically ill patients with COVID-19—A multicenter cohort study
	22% higher mortality (p=0.25), 27% higher ventilation (p=0.05), 17% higher ICU admission (p=0.07), and no change in hospitalization (p=1). Retrospective 1,435 ICU patients in Saudi Arabia, showing no significant difference in mortality, and longer mechanical ventilation with treatment. Vitamin D patients had higher Q1, median, and Q3 SOFA scores after propensity score matchi..
Aug 11 2023	Sposito et al., Mucosal Immunology, doi:10.1016/j.mucimm.2023.08.002	Age differential CD13 and interferon expression in airway epithelia affect SARS-CoV-2 infection - effects of vitamin D
	In vitro study showing that vitamin D reduced SARS-CoV-2 replication in adult nasal epithelial cells via increased type I interferon expression. Administration of vitamin D by systemic supplementation or direct nasal delivery may be benef..
Aug 10 2023	Chen et al., Journal of Trace Elements in Medicine and Biology, doi:10.1016/j.jtemb.2023.127278	Effects of vitamin D and zinc deficiency in acute and long COVID syndrome
	Retrospective 55 patients with long COVID, showing vitamin D deficiency associated with delayed recovery.
Aug 9 2023	Abdulameer et al., Cellular and Molecular Biology, doi:10.14715/cmb/2023.69.5.5	The vitamin D binding protein gene polymorphism association with Covid-19-infected Iraqi patients
	Case control study of 150 COVID-19 patients and 150 healthy controls showing that COVID-19 patients had significantly lower vitamin D levels, and that the DBP gene polymorphism rs12785878 TG genotype was associated with higher risk of COV..
Aug 9 2023	Gotelli et al., Neuroimmunomodulation, doi:10.1159/000533286	Understanding the immune-endocrine effects of vitamin D in SARS-CoV-2 infection: a role in protecting against neurodamage?
	Review of the potential benefits of vitamin D for COVID-19 in relation to neuroprotection. Authors note that neurological symptoms are common in COVID-19, likely related to disruption of the blood-brain barrier, inflammation, and immunoth..
Aug 8 2023	Mayurathan et al., Asian Journal of Internal Medicine, 2:2	Association of vitamin D levels with severity and outcome of COVID-19 infection among inward patients at a tertiary care unit in Sri Lanka
	98% higher mortality (p=0.69) and 67% higher severe cases (p=0.32). Retrospective 141 hospitalized patients in Sri Lanka, showing lower mortality and severity with vitamin D deficiency, without statistical significance. Authors state that "studies regarding the correlation between vitamin D and CO..
Aug 3 2023	Aci et al., Nucleosides, Nucleotides & Nucleic Acids, doi:10.1080/15257770.2023.2253281	Effect of vitamin D receptor gene BsmI polymorphism on hospitalization of SARS-CoV-2 positive patients
	Analysis of 80 COVID-19 hospitalized patients and 110 healthy controls, showing lower vitamin D levels in COVID-19 patients. The vitamin D receptor gene BsmI b allele and bb genotype were associated with hospitalization. Authors note this..
Jul 30 2023	Mingiano et al., Nutrients, doi:10.3390/nu15153392	Vitamin D Deficiency in COVID-19 Patients and Role of Calcifediol Supplementation
	39% lower mortality (p=0.04), 23% lower need for oxygen therapy (p=0.22), and 35% shorter hospitalization (p=0.01). Retrospective 288 hospitalized COVID-19 patients in Italy, showing lower mortality and shorter hospitalization with calcifediol. Results may underestimate the benefits because only higher risk patients with vitamin D deficiency received..
Jul 26 2023	Umay et al., Journal of Contemporary Medicine, doi:10.16899/jcm.1319088	Comparison of Length of Hospital Stay and Routine Laboratory Parameters in Covid-19 Patients With and Without Serum Vitamin D Deficiency
	13% shorter hospitalization (p=0.33). Retrospective 413 hospitalized COVID-19 patients in Turkey showing vitamin D deficiency associated with higher CRP, fibrinogen, neutrophils, and hematocrit. There was no significant difference for length of stay.
Jul 26 2023	Ramírez-Stieben et al., Gaceta Médica de México, doi:10.24875/gmm.m23000770	25(OH)D levels during the COVID-19 pandemic: impact of lockdown and ultraviolet radiation
	Analysis of the impact of COVID-19 lockdown policies on vitamin D levels in Argentina. Vitamin D levels were lower in 2020 compared to 2019, especially during the first wave of COVID-19 from September-November 2020. Levels decreased after..
Jul 25 2023	Moghaddam et al., Journal of Health, Population and Nutrition, doi:10.1186/s41043-023-00409-y	High-dose vitamin D supplementation is related to an improvement in serum alkaline phosphatase in COVID-19 patients; a randomized double-blinded clinical trial
	RCT 140 hospitalized patients in Iran, showing patients treated with high dose vitamin D had a significant decrease in serum alkaline phosphatase compared to the control group receiving lower dose vitamin D. No significant differences wer..
Jul 17 2023	Shamsi et al., Canadian Journal of Infectious Diseases and Medical Microbiology, doi:10.1155/2023/5205188	Survival and Mortality in Hospitalized Children with COVID-19: A Referral Center Experience in Yazd, Iran
	58% lower mortality (p=0.7). Retrospective 183 hospitalized pediatric COVID-19 patients in Iran, showing no significant difference in mortality with in unadjusted results.
Jul 15 2023	Graydon et al., Current Research in Immunology, doi:10.1016/j.crimmu.2023.100064	High baseline frequencies of natural killer cells are associated with asymptomatic SARS-CoV-2 infection
	Analysis of 88 COVID+ patients in the USA showing that a higher frequency of natural killer (NK) cells was associated with asymptomatic infection. Improved NK cell numbers and functioning has been shown for exercise [Oh], better sleep [Ir..
Jul 11 2023	Arayafar et al., Annals of Medicine & Surgery, doi:10.1097/MS9.0000000000000955	Vitamin D status and blood group among severe COVID19 patients
	Retrospective 305 COVID-19 ICU patients in Iran, showing vitamin D deficiency associated with mortality.
Jul 11 2023	Partap et al., Current Developments in Nutrition, doi:10.1016/j.cdnut.2023.101971	Vitamin D and zinc supplementation to improve treatment outcomes among COVID-19 patients in India: results from a double-blind randomized placebo-controlled trial
	3% higher ventilation (p=0.91), 14% higher hospital discharge (p=0.53), and 11% improved recovery (p=0.65). Early terminated factorial RCT with 46 vitamin D, 48 zinc, 44 vitamin D + zinc, and 43 placebo patients in India. The most serious outcome (ventilation) numbers do not seem realistic. Authors do not specify outcomes per group, but with on..
Jul 6 2023	Aghajani et al., Frontiers in Nutrition, doi:10.3389/fnut.2023.1174113	Association between dietary antioxidant quality score and severity of coronavirus infection: a case–control study
	Case control study of 295 COVID-19 patients in Iran, showing lower risk of severe cases with higher dietary antioxidant quality scores, and with higher intake of vitamin D.
Jun 30 2023	Saha et al., Exploratory Animal and Medical Research, doi:10.52635/eamr/13.1.16-21	Vitamin D status in Covid-19 patients admitted to the critical care unit of an Eastern India hospital
	Analysis of 97 COVID-19 CCU patients in India. Patients with severe COVID-19 had significantly lower vitamin D levels compared to those with moderate COVID-19. There was a significant correlation between lower vitamin D levels and more se..
Jun 30 2023	Sanecka et al., Nutrients, doi:10.3390/nu15132976	Hospital Outcomes in Patients Hospitalized for COVID-19 Pneumonia: The Effect of SARS-CoV-2 Vaccination and Vitamin D Status
	Prospective study of 171 hospitalized COVID-19 patients in Ireland, showing significantly lower mortality and ICU admission with sufficient vitamin D levels among unvaccinated patients. There were no significant differences for vaccinated..
Jun 22 2023	Cao et al., Frontiers in Nutrition, doi:10.3389/fnut.2023.1132528	The effects of vitamin D on all-cause mortality in different diseases: an evidence-map and umbrella review of 116 randomized controlled trials
	Meta analysis showing significantly lower mortality for COVID-19 patients with vitamin D treatment, however it's not clear why Annweiler et al. is considered an RCT, or why most of the COVID-19 vitamin D RCTs are not included.
Jun 21 2023	Chen et al., MedComm, doi:10.1002/mco2.318	Vitamin D3 attenuates SARS‐CoV‐2 nucleocapsid protein‐caused hyperinflammation by inactivating the NLRP3 inflammasome through the VDR‐BRCC3 signaling pathway in vitro and in vivo
	In vitro and mouse study showing that vitamin D3 attenuates SARS-CoV-2 nucleocapsid protein-induced hyperinflammation by inactivating the NLRP3 inflammasome through the VDR-BRCC3 signaling pathway. In human bronchial epithelial cells over..
Jun 20 2023	Mahjoub et al., Explore, doi:10.1016/j.explore.2023.06.009	Melatonin, vitamins and minerals supplements for the treatment of Covid-19 and Covid-like illness: a prospective, randomized, double-blind multicenter study.
	67% improved recovery (p=0.32). RCT 164 low-risk (no hospitalizations) patients in Tunisia, showing improved recovery with zinc, melatonin, and vitamins A-E. This study includes COVID-19 and COVID-like illness, with 49% of 128 patients receiving a PCR test being COVID-1..
Jun 16 2023	Salman et al., Biological and Clinical Sciences Research Journal, doi:10.54112/bcsrj.v2023i1.322	Role of vitamin-D supplementation in COVID-19 patients
	60% lower mortality (p=0.07), 17% lower ventilation (p=0.55), 12% lower ICU admission (p=0.85), and 18% shorter hospitalization (p=0.001). RCT 300 hospitalized COVID-19 patients in Pakistan receiving either 4,000 IU vitamin D3 supplementation or standard care daily for 14 days. The vitamin D group had significantly faster time to clinical improvement (7 vs 9 days) and shorte..
Jun 15 2023	Frish et al., Journal of Clinical Medicine, doi:10.3390/jcm12124054	The Association of Weight Reduction and Other Variables after Bariatric Surgery with the Likelihood of SARS-CoV-2 Infection
	35% fewer cases (p=0.001). Retrospective 3,038 bariatric surgery patients in Israel, showing higher risk of SARS-CoV-2 infection with vitamin D deficiency, and lower risk with physical activity.
Jun 15 2023	Manojlovic et al., European Review for Medical and Pharmacological Sciences, doi:10.26355/eurrev_202306_32651	Association between vitamin D hypovitaminosis and severe forms of COVID-19
	90% lower mortality (p=0.009). Retrospective 74 COVID-19 patients in Serbia, showing higher mortality with severe vitamin D deficiency in unadjusted results. Patients with severe deficiency were older (63.7 vs. 52.8).
Jun 14 2023	Orellana-Manzano et al., Frontiers in Pharmacology, doi:10.3389/fphar.2023.1197973	A report on SARS-CoV-2 first wave in Ecuador: drug consumption dynamics
	Retrospective 10,175 people PCR tested in Ecuador, showing lower risk of PCR+ with multivitamin use and suggesting higher risk with acetaminophen use. The study analyzed drug consumption for COVID-19 symptoms during the 14 days before the..
Jun 1 2023	Jalavu et al., IJID Regions, doi:10.1016/j.ijregi.2023.05.007	An investigation of the correlation of vitamin D status and management outcomes in patients with severe COVID-19 at a South African tertiary hospital
	1% lower mortality (p=0.97). Prospective analysis of 68 COVID-19 ICU patients in South Africa, showing a high prevalence of vitamin D deficiency/insufficiency. There was no significant difference in mortality based on vitamin D sufficiency, however this result does n..
Jun 1 2023	Wani et al., Intervirology, doi:10.1159/000530906	Impact of Age and Clinico-Biochemical Parameters on Clinical severity of SARS-CoV-2 Infection
	72% lower severe cases (p=0.007). Retrospective 236 COVID-19 patients in India, showing higher risk of severe cases with vitamin D deficiency.
May 31 2023	Jain et al., Journal of Cardiovascular Disease Research, doi:10.31838/jcdr.2023.14.05.215	Demographical Profile and Clinical Outcomes of Covid-19 Patients at a Tertiary Care Centre
	Retrospective 100 COVID-19 patients in India, showing higher vitamin D levels associated with survival and lower severity in unadjusted results.
May 29 2023	Saeed et al., University of Thi-Qar Journal of Medicine, 25:1	Vitamin D Deficiency and Clinical Outcomes in Patients with COVID-19
	Analysis of 59 COVID-19 patients and 25 healthy controls in Iraq, showing lower vitamin D levels in COVID-19 patients.
May 25 2023	Ducharme et al., BMJ Open, doi:10.1136/bmjopen-2022-064058	Prevention of COVID-19 with oral vitamin D supplemental therapy in essential healthcare teams (PROTECT): protocol for a multicentre, triple-blind, randomised, placebo-controlled trial
	Report on the PROTECT vitamin D prophylaxis trial for healthcare workers, terminated after 34 patients and providing no results. Authors indicate the trial was terminated for low enrollment due to high use of vitamin D and a high concurre..
May 21 2023	Chen et al., Nutrition, doi:10.1016/j.nut.2023.112087	Early oral nutritional supplement improves COVID-19 outcomes among hospitalized older patients during the omicron wave
	PSM retrospective 1,181 COVID-19 patients ≥60 years old in China, showing significantly lower mortality with a nutritional supplement. Hospitalization time and viral clearance time was improved with earlier initiation of treatment. The su..
May 12 2023	Pop-Kostova et al., Medical Journal MEDICUS, 28:1	Vitamin D status in patients with COVID-19 – sex differences associated with severity of the disease
	Retrospective 115 COVID-19 patients in North Macedonia, showing lower vitamin D levels associated with hospitalization.
May 12 2023	Repas et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2023.106329	Normal 24-hour Urine Calcium Concentrations after Long-term Daily Oral Intake of Vitamin D in Doses Ranging from 5000 to 50,000 International Units in 14 Adult Hospitalized Psychiatric Patients
	Retrospective psychiatric patients in the USA finding that prolonged daily oral intake of vitamin D3 from 5,000 to 10,000 IU/day was safe. There was no evidence for hypercalcemia, renal failure, calcium crystal formation, nephrolithiasis...
May 3 2023	Capraru et al., Medicina, doi:10.3390/medicina59050877	COVID-19 Biomarkers Comparison: Children, Adults and Elders
	Retrospective 1,376 patients in Romania, showing vitamin D levels inversely related to COVID-19 symptoms, severity, ICU admission, and death.
May 3 2023	Hogarth et al., The American Journal of the Medical Sciences, doi:10.1016/j.amjms.2023.04.019	Clinical Characteristics and Comorbidities associated with SARS-CoV-2 breakthrough infection in the University of California Healthcare Systems
	47% fewer cases (p<0.0001). Retrospective 110,380 patients in the USA, showing higher risk of COVID-19 breakthrough cases with vitamin D deficiency. Authors note that "lockdown measures pose an increased risk for individuals to develop vitamin D deficiency"..
May 1 2023	Taslim et al., Nutr. clín. diet. hosp., doi:10.12873/432taslim	The Effects of 10,000 IU Vitamin D Supplementation on Improvement of Clinical Outcomes, Inflammatory and Coagulation Markers in Moderate COVID-19 Patients: A Randomized-Controlled Trial
	71% lower need for oxygen therapy (p=0.01), 21% shorter hospitalization (p=0.0002), and 38% faster viral clearance (p<0.0001). RCT 72 moderate COVID-19 patients with vitamin D deficiency or insufficiency in Indonesia, showing faster viral clearance and improved recovery with 10,000IU vitamin D vs. 1,000IU vitamin D. Higher vitamin D levels were associated with sh..
Apr 30 2023	Sanamandra et al., Indian Journal of Endocrinology and Metabolism, doi:10.4103/ijem.ijem_383_22	Correlation between Serum Vitamin D3 levels and severity of COVID-19, experience from a COVID-19-dedicated tertiary care hospital from Western India
	21% lower mortality (p=0.67), 15% lower ventilation (p=0.73), and 435% higher severe cases (p=0.13). Prospective analysis of 200 hospitalized COVID-19 patients in India, showing no significant differences in outcomes with vitamin D deficiency.
Apr 28 2023	Ritsinger et al., BMJ Open, doi:10.1136/bmjopen-2022-069037	History of heart failure and chronic kidney disease and risk of all-cause death after COVID-19 during the first three waves of the pandemic in comparison with influenza outbreaks in Sweden: a registry-based, retrospective, case–control study
	9% lower mortality (p<0.0001). Retrospective 44,866 hospitalized COVID-19 patients in Sweden, showing higher mortality with vitamin D deficiency and with acetaminophen use. The study focuses on cardiorenal disease, finding higher risk of mortality with CRD. Authors als..
Apr 26 2023	Gholamalizadeh et al., Immunity, Inflammation and Disease, doi:10.1002/iid3.844	The association between vitamin D intake with inflammatory and biochemical indices and mortality in critically ill patients with COVID‐19: A case‐control study
	69% lower mortality (p=0.04). Case control study with 200 critical COVID-19 patients in Iran, showing lower mortality with higher vitamin D supplement intake. Authors do not provide enough information to assess confounding. Authors indicate that treatment was based on..
Apr 25 2023	Al Balwi et al., Annals of Thoracic Medicine, doi:10.4103/atm.atm_435_22	Risk factors predicting disease severity and mortality in coronavirus disease 2019 Saudi Arabian patients
	Retrospective 206 COVID-19 patients in Saudi Arabia, showing no significant difference in vitamin D levels based on survival.
Apr 25 2023	Jaun et al., Biomedicines, doi:10.3390/biomedicines11051277	Effect of Single High Dose Vitamin D Substitution in Hospitalized COVID-19 Patients with Vitamin D Deficiency on Length of Hospital Stay
	300% higher ventilation (p=0.2). RCT late stage patients showing no significant differences with the addition of single dose 140,000IU vitamin D treatment. All patients received vitamin D 800IU daily. There was a non-significant shorter length of stay for patients with v..
Apr 25 2023	Asla et al., Current Research in Nutrition and Food Science Journal, doi:10.12944/CRNFSJ.11.1.3	Vitamin D on COVID-19 Patients During the Pandemic, 2022. A Systematic Review and Meta-Analysis
	36% lower mortality (p=0.01), 30% lower ventilation (p=0.001), and 52% lower ICU admission (p=0.02). Systematic review and meta-analysis of 42 studies with 8,001 COVID-19 patients showing vitamin D deficiency associated with higher mortality, and vitamin D supplementation associated with lower mortality, ICU admission, mechanical ventila..
Apr 24 2023	Baralić et al., Nutrients, doi:10.3390/nu15092050	Significance of 1,25-Dihydroxyvitamin D3 on Overall Mortality in Peritoneal Dialysis Patients with COVID-19
	67% lower mortality (p=0.02). Prospective analysis of 52 peritoneal dialysis patients, 31 on calcitriol (vitamin D) therapy. All patients tested positive for COVID-19 during followup (median 26 months). Mortality was significantly lower for patients on calcitriol ther..
Apr 19 2023	Agüero-Domenech et al., Nutrients, doi:10.3390/nu15081972	Influence of Strict Lockdown on Vitamin D Deficiency in Pregnant Women: A Word of Caution
	Retrospective 886 pregnant women in Spain, showing that strict lockdowns increased the risk of vitamin D deficiency.
Apr 19 2023	Beheshti et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2023.04.012	Correlation of vitamin D levels with serum parameters in Covid-19 patients
	Retrospective 140 COVID-19 patients in Iran showing lower vitamin D levels associated with hospitalization.
Apr 17 2023	Abdulrahman et al., The International Journal of Psychiatry in Medicine, doi:10.1177/00912174231171220	Correlates of poor clinical outcomes related to COVID-19 among older people with psychiatric illness - a mixed methods study
	90% lower mortality (p=0.05) and 82% lower progression (p=0.09). Retrospective 81 pyschiatric inpatients in the UK, mean age 76, showing vitamin D deficiency associated with COVID-19 mortality.
Apr 15 2023	Devi et al., International Journal of Clinical Biochemistry and Research, doi:10.18231/j.ijcbr.2023.007	Vitamin D in COVID-19
	98% fewer cases (p=0.007). Retrospective 88 PCR+ COVID-19 cases and 88 matched COVID-19 negative controls in India showing lower vitamin D levels and higher prevalence of vitamin D deficiency in COVID-19 patients.
Apr 13 2023	Rachman et al., F1000Research, doi:10.12688/f1000research.132214.4	The association between vitamin D deficiency and the clinical outcomes of hospitalized COVID-19 patients
	95% lower mortality (p=0.04) and 78% lower severe cases (p=0.01). Prospective study of hospitalized patients in Indonesia, showing higher risk of mortality and severe cases with vitamin D deficiency.
Apr 13 2023	di Filippo et al., The Journal of Clinical Endocrinology & Metabolism, doi:10.1210/clinem/dgad207	Low vitamin D levels are associated with Long COVID syndrome in COVID-19 survivors
	Retrospective 50 COVID-19 patients with long COVID and 50 matched patients without long COVID, showing lower vitamin D levels associated with long COVID.
Apr 11 2023	Rybakovsky et al., Physiological Reports, doi:10.14814/phy2.15592	Calcitriol modifies tight junctions, improves barrier function, and reduces TNF‐α‐induced barrier leak in the human lung‐derived epithelial cell culture model, 16HBE 14o‐
	In vitro study showing that calcitriol improved barrier function in human airway epithelial cells. Authors note that this mechanism could explain in part the efficacy of vitamin D seen for COVID-19 and other airway diseases.
Apr 6 2023	Fernandes de Souza et al., Cells, doi:10.3390/cells12071092	Lung Inflammation Induced by Inactivated SARS-CoV-2 in C57BL/6 Female Mice Is Controlled by Intranasal Instillation of Vitamin D
	C57BL/6 mouse study showing intranasal administration of vitamin D decreased inflammation following intranasal inactivated SARS-CoV-2. Authors suggest a promising potential of intranasal vitamin D to control pulmonary inflammation associa..
Apr 6 2023	Protas et al., Nutrients, doi:10.3390/nu15071781	Plasma 25-Hydroxyvitamin D Level and VDR Gene Single Nucleotide Polymorphism rs2228570 Influence on COVID-19 Susceptibility among the Kazakh Ethnic Group—A Pilot Study
	77% fewer cases (p=0.06). Retrospective 119 patients in Kazakhstan, showing significantly lower vitamin D levels in COVID-19 patients. There was an association between rs2228570 of the VDR gene and COVID-19. The C allele was associated with reduced likelihood of C..
Apr 6 2023	Azmi et al., Molecular Genetics & Genomic Medicine, doi:10.1002/mgg3.2172	The role of vitamin D receptor and IL‐6 in COVID‐19
	Retrospective 120 hospitalized COVID-19 patients and 120 controls, showing no significant difference in vitamin D levels, however vitamin D receptor gene expression was significantly lower in COVID-19 patients. Vitamin D receptor (VDR) ge..
Apr 5 2023	Bayrak et al., Turkish Archives of Pediatrics, doi:10.5152/turkarchpediatr.2023.22217	Association Between Vitamin D Levels and COVID-19 Infection in Children: A Case-Control Study
	33% fewer cases (p=0.23). Retrospective 73 COVID-19 and 76 healthy pediatric patients in Turkey, showing significantly lower vitamin D levels in COVID-19 patients.
Apr 1 2023	Reino-Gelardo et al., Nutrients, doi:10.3390/nu15071736	Effect of an Immune-Boosting, Antioxidant and Anti-Inflammatory Food Supplement in Hospitalized COVID-19 Patients: A Prospective Randomized Pilot Study
	61% lower mortality (p=0.05). RCT 162 late stage (65% on oxygen) patients in Spain, 78 treated with probiotics, prebiotics, vitamin D, zinc, and selenium, showing lower mortality with treatment, statistically significant only within the patients with high severity at ..
Mar 31 2023	DiGuilio et al., Experimental Lung Research, doi:10.1080/01902148.2023.2193637	The multiphasic TNF-α-induced compromise of Calu-3 airway epithelial barrier function
	In vitro study showing that TNF-α induced a multiphasic transepithelial leak in Calu-3 cell layers, and that vitamin A and vitamin D (calcitriol) were effective at reducing the barrier compromise caused by TNF-α.
Mar 29 2023	Aweimer et al., Scientific Reports, doi:10.1038/s41598-023-31944-7	Mortality rates of severe COVID-19-related respiratory failure with and without extracorporeal membrane oxygenation in the Middle Ruhr Region of Germany
	21% lower mortality (p=0.31). Retrospective 149 patients under invasive mechanical ventilation in Germany showing no significant difference in mortality with vitamin D prophylaxis in unadjusted results.
Mar 29 2023	Wang et al., Scientific Reports, doi:10.1038/s41598-024-66267-8 (date from preprint)	Randomized trial of influence of vitamin D on the prevention and improvement of symptomatic COVID-19
	25% lower progression (p=0.15), 4% fewer cases (p=0.89), and 11% faster viral clearance. RCT 214 low risk (no hospitalization) healthcare workers in China, showing no significant differences with vitamin D2 prophylaxis using two bolus treatments. Patients with higher vitamin D levels (across both groups) were less likely to b..
Mar 28 2023	Hermawan et al., Molecular and Cellular Biomedical Sciences, doi:10.21705/mcbs.v7i1.306	Association between 25(OH)D3 Levels and the Presence of COVID-19 Symptoms
	71% fewer symptomatic cases (p<0.0001). Retrospective 47 patients in Indonesia showing lower vitamin D levels associated with increased COVID-19 symptoms. Adjusted results are only provided for vitamin D levels as a continuous value.
Mar 28 2023	Us et al., Pediatrics International, doi:10.1111/ped.15680 (date from preprint)	The role of free vitamin D and vitamin D binding protein in SARS‐Cov‐2 infection in children
	Prospective study of 82 pediatric patients in Turkey, showing symptom severity associated with free vitamin D and bioavailable vitamin D levels.
Mar 28 2023	Cutolo et al., Nature Reviews Rheumatology, doi:10.1038/s41584-023-00944-2	Involvement of the secosteroid vitamin D in autoimmune rheumatic diseases and COVID-19
	Review of the role of vitamin D in autoimmune rheumatic diseases and COVID-19. For COVID-19, vitamin D deficiency is associated with increased risk of infection and severe outcomes. Authors discuss the immunomodulatory effects of vitamin ..
Mar 27 2023	Sposato et al., Epidemiol Prev., doi:10.19191/EP23.1.A503.016	COVID-19 severity appears to be reduced in spring/summer
	Retrospective 8,221 COVID+ patients in Italy, showing significantly lower ICU admission and CPAP/NIV use in the spring/summer compared to the winter. There was no significant difference in viral load. Vitamin D levels were higher and CRP ..
Mar 24 2023	Cetin Ozbek et al., Clinical Science of Nutrition, doi:10.5152/ClinSciNutr.2023.22059	Does the Level of Vitamin D in COVID-19 Patients Affect the Survival and Duration of Hospital Stay?
	51% lower mortality (p=0.07). Retrospective 168 hospitalized COVID-19 patients, showing no significant association between vitamin D levels and mortality. Adjusted results are only provided for vitamin D as a continuous variable.
Mar 24 2023	Basińska-Lewandowska et al., Nutrients, doi:10.3390/nu15071581	Frequency of COVID-19 Infection as a Function of Vitamin D Levels
	58% fewer cases (p=0.02). Retrospective 134 patients in Poland between ages 6-50, showing higher risk of COVID-19 cases with vitamin D levels <12 ng/mL.
Mar 24 2023	Huang et al., Frontiers in Medicine, doi:10.3389/fmed.2023.1121256	Effect of vitamin D status on adult COVID-19 pneumonia induced by Delta variant: A longitudinal, real-world cohort study
	25% faster recovery (p=0.02). Retrospective COVID-19 pneumonia patients in China, showing slower recovery with vitamin D deficiency.
Mar 22 2023	Schmidt et al., Journal of Clinical Medicine, doi:10.3390/jcm12062429	Identification of Clinical Response Predictors of Tocilizumab Treatment in Patients with Severe COVID-19 Based on Single-Center Experience
	86% lower mortality (p=0.003). Prospective study of 120 severe COVID-19 patients in Poland treated with tocilizumab, showing significantly higher mortality with low vitamin D levels.
Mar 17 2023	Cui et al., Frontiers in Nutrition, doi:10.3389/fnut.2023.1070808	Global and regional prevalence of vitamin D deficiency in population-based studies from 2000 to 2022: A pooled analysis of 7.9 million participants
	Meta analysis of the global and regional prevalence of vitamin D deficiency from 308 studies, showing that globally 48% of people had vitamin D levels <50 nmol/l. The prevalence in winter-spring was 1.7 times that in summer-autum.
Mar 15 2023	Davran et al., Konuralp Tıp Dergisi, doi:10.18521/ktd.1134319	Relationship between vitamin D level and clinical status in COVID-19 patients
	75% lower mortality (p=0.02). Retrospective 47 outpatient and 47 hospitalized COVID-19 patients in Turkey, showing higher mortality with vitamin D deficiency in unadjusted results.
Mar 15 2023	Schloss et al., Inflammopharmacology, doi:10.1007/s10787-023-01183-3	Nutritional deficiencies that may predispose to long COVID
	Review of 22 nutritional factors that have been linked to COVID-19 outcomes, the role of nutrients in COVID-19 infection, and the prevalence of multiple nutritional deficiencies in the population.
Mar 14 2023	Dong et al., Frontiers in Public Health, doi:10.3389/fpubh.2023.1048087	Comparison of anthropometric parameters and laboratory test results before and after the COVID-19 outbreak among Chinese children aged 3–18 years
	Retrospective 2,162 children 3-18 in China, showing 2.8 times greater vitamin D deficiency, and increased obesity, hypercholesterol, and hyperuricemia after extended COVID-19 lockdown in China.
Mar 13 2023	Gonzalez et al., Revista de Nutrición Clínica y Metabolismo, doi:10.35454/rncm.v6n2.485	Vitamin D on admission and disease severity in patients with COVID-19 in the Intensive Care Unit
	66% lower mortality (p=0.05). Retrospective 164 ICU patients in Argentina, showing significantly higher mortality with severe vitamin D deficiency.
Mar 9 2023	Siuka et al., F1000Research, doi:10.12688/f1000research.131730.1	The effect of Vitamin D levels on the course of COVID-19 in hospitalized patients – a 1-year prospective cohort study
	56% lower mortality (p=0.24), 59% higher ICU admission (p=0.59), and 61% higher severe cases (p=0.009). Prospective study of 301 hospitalized patients in Slovenia, showing higher mortality with vitamin D deficiency, without statistical significance. Fewer patients with severe cases were deficient, which authors hypothesize was due to their..
Mar 6 2023	Bucurica et al., Diagnostics, doi:10.3390/diagnostics13050998	Association of Vitamin D Deficiency and Insufficiency with Pathology in Hospitalized Patients
	28% fewer cases (p<0.0001). Retrospective 11,182 hospitalized patients in Romania, showing vitamin D deficiency associated with COVID-19 cases.
Mar 6 2023	Bhat et al., Journal of Infection, doi:10.1016/j.jinf.2023.03.004	Effect of calcifediol supplementation as add-on therapy on the immune repertoire in recipients of the ChAdOx1 nCoV-19 vaccine: A prospective open-label, placebo-controlled, clinical trial
	34% fewer symptomatic cases (p=0.01). Prospective study of 580 ChAdOx1 recipients, 262 treated with calcifediol (patient choice), showing lower cases with treatment. Supplementation did not significantly affect antibody levels following ChAdOx1 receipt. Calcifediol patients w..
Mar 5 2023	Liu et al., The Journal of Nutrition, doi:10.1016/j.tjnut.2023.03.001	Vitamin D and SARS-CoV-2 Infection: SERVE Study (SARS-CoV-2 Exposure and the Role of Vitamin D among Hospital Employees)
	Prospective study of 250 healthcare workers in the USA. The results are unclear - Figure 3 shows ~40% lower incidence with vitamin D supplementation, while the text indicates OR 1.18. Authors collected symptom information, stating that &q..
Mar 3 2023	Al-Gharrawi et al., Scientific Reports, doi:10.1038/s41598-023-30859-7	Association of ApaI rs7975232 and BsmI rs1544410 in clinical outcomes of COVID-19 patients according to different SARS-CoV-2 variants
	Retrospective 3,184 patients in Iran, showing COVID-19 outcomes for specific variants were associated with genotypes of the ApaI rs7975232 and BsmI rs1544410 vitamin D receptor polymorphisms.
Feb 28 2023	Boukef et al., NCT05670444	Melatonin, Vitamins and Minerals Supplements for the Treatment of Covid-19 and Covid-like Illness: Results of a Prospective, Randomised, Double-blinded Multicentre Study
	150 patient vitamin D early treatment RCT with results not reported over 3 years after completion.
Feb 28 2023	Arabadzhiyska et al., Bratislava Medical Journal, doi:10.4149/bll_2023_069	Serum vitamin D levels and inflammatory status in COVID-19 patients
	30% lower severe cases (p=0.16). Retrospective 100 hospitalized COVID-19 patients in Bulgaria and 40 healthy controls, showing significantly lower vitamin D levels in COVID-19 patients, and lower levels in patients with severe vs. moderate disease.
Feb 28 2023	Topan et al., Nutrients, doi:10.3390/nu15051227	25 Hydroxyvitamin D Serum Concentration and COVID-19 Severity and Outcome—A Retrospective Survey in a Romanian Hospital
	31% lower mortality (p=0.02) and 11% lower severe cases (p=0.02). Retrospective 2,342 hospitalized COVID-19 patients in Romania with vitamin D levels measured on admission day, showing lower risk of mortality and severe/critical cases with vitamin D levels ≥ 20ng/mL.
Feb 28 2023	Domazet Bugarin et al., Nutrients, doi:10.3390/nu15051234	Vitamin D Supplementation and Clinical Outcomes in Severe COVID-19 Patients—Randomized Controlled Trial
	21% lower mortality (p=0.2), no change in recovery (p=0.71), and 6% longer hospitalization (p=0.76). Very late stage RCT 155 ICU patients in Croatia with low vitamin D levels, showing no significant differences with 10,000IU cholecalciferol daily. Calcifediol or calcitriol, which avoids several days delay in conversion, may be more succe..
Feb 28 2023	Chen et al., Infection and Drug Resistance, doi:10.2147/idr.s400561	Plasma 25(OH)D Level is Associated with the Nucleic Acid Negative Conversion Time of COVID-19 Patients: An Exploratory Study
	40% improved viral clearance (p=0.01). Retrospective 158 COVID+ patients in China, showing low vitamin D levels associated with slower viral clearance.
Feb 27 2023	Bader et al., Nutrients, doi:10.3390/nu15051188	The Effect of Weekly 50,000 IU Vitamin D3 Supplements on the Serum Levels of Selected Cytokines Involved in Cytokine Storm: A Randomized Clinical Trial in Adults with Vitamin D Deficiency
	RCT 100 patients in Jordan, showing that high-dose cholecalciferol (50,000 IU/week) significantly increased IL-6, indicating that high weekly doses could have a negative effect for cytokine storm with COVID-19. Other studies have found no..
Feb 27 2023	Tan et al., Journal of the ASEAN Federation of Endocrine Societies, doi:10.15605/jafes.038.01.07	Association of Vitamin D levels on the Clinical Outcomes of Patients Hospitalized for COVID-19 in a Tertiary Hospital
	71% lower progression (p=0.04), 91% lower mortality (p=0.002), and 82% lower ICU admission (p=0.01). Retrospective 135 hospitalized COVID-19 patients in the Philippines, showing higher risk of a poor outcome with vitamin D deficiency.
Feb 16 2023	Montini et al., Journal of Neurology, doi:10.1007/s00415-023-11618-0	Modifiable risk factors of COVID-19 in patients with multiple sclerosis: a single-centre case–control study
	Case control analysis with 149 multiple sclerosis patients and 292 matched controls in Italy, showing lower risk of COVID-19 cases with higher vitamin D levels.
Feb 15 2023	Xie et al., Critical Reviews in Food Science and Nutrition, doi:10.1080/10408398.2023.2174948	Micronutrient perspective on COVID-19: Umbrella review and reanalysis of meta-analyses
	Systematic review and meta analysis of micronutrient supplementation, showing vitamin D supplementation associated with lower mortality, mechanical ventilation, ICU admission, and severity. Note that forest plots have OR>1 favoring supple..
Feb 14 2023	Ortatatli et al., Archives of Medical Research, doi:10.1016/j.arcmed.2023.02.002	Potential Role of Vitamin D, ACE2 and the Proteases as TMPRSS2 and Furin on SARS-CoV-2 Pathogenesis and COVID-19 Severity
	82% lower mortality (p=0.09). Analysis of 68 COVID-19 patients and 17 healthy controls, showing higher mortality with vitamin D deficiency, and with 1,25(OH)2D levels <1 ng/mL, statistically significant only for 1,25(OH)2D levels. Serum ACE2, 1,25(OH)2D, and ACE2 mRNA..
Feb 13 2023	D’Alessandro et al., Scientific Reports, doi:10.1038/s41598-023-29519-7	Contribution of vitamin D3 and thiols status to the outcome of COVID-19 disease in Italian pediatric and adult patients
	Retrospective 173 patients in Italy showing significantly lower glutathione levels and high prevalence of vitamin D deficiency in COVID-19 patients, and lower levels of glutathione and vitamin D associated with mortality. Acetaminophen (p..
Feb 2 2023	Arora et al., Nutrients, doi:10.3390/nu15030771	Global Dietary and Herbal Supplement Use during COVID-19—A Scoping Review
	Review of 14 global studies showing that the most frequently used dietary supplements during COVID-19 were vitamin C, vitamin D, zinc, and multivitamins. The most common reason was for improved immune system functioning or reduced COVID-1..
Jan 30 2023	Sallam et al., Journal of Food and Nutrition Research, doi:10.12691/jfnr-11-1-10	Dietary Supplement Use among Children Whose Parents Work at National Research Centre: A Pilot Study
	Survey of dietary supplementation showing high usage, and greater use by more highly educated people. The survey covered 200 children whose parents were employees of a research center in Egypt, showing 50% prevalence of supplementation du..
Jan 24 2023	Rathod et al., Annals of African Medicine, doi:10.4103/aam.aam_21_22	Association of vitamin D with the severity of disease and mortality in COVID-19: Prospective study in central India
	Prospective study of 766 hospitalized patients in India, showing higher vitamin D levels associated with lower COVID-19 severity and mortality.
Jan 22 2023	Arabi et al., Journal of Renal Injury Prevention, doi:10.34172/jrip.2022.32126	The association between vitamin D3 deficiency and acute kidney injury in COVID-19 patients
	40% lower mortality (p=0.28), 39% lower ICU admission (p=0.2), and 42% improvement (p=0.13). Retrospective 69 hospitalized COVID-19 patients in Iran, showing lower vitamin D associated with higher mortality, ICU admission, and AKI in unadjusted results. The mean age of deficient patients was lower. Statistical significance is not..
Jan 18 2023	Din Ujjan et al., Frontiers in Nutrition, doi:10.3389/fnut.2022.1023997	The possible therapeutic role of curcumin and quercetin in the early-stage of COVID-19—Results from a pragmatic randomized clinical trial
	29% improved recovery (p=0.11) and 91% improved viral clearance (p=0.05). Small RCT with 50 outpatients, 25 treated with curcumin, quercetin, and vitamin D, showing improved recovery and viral clearance with treatment. 168mg curcumin, 260mg, 360IU vitamin D3 daily for 14 days. Unadjusted baseline differences: t..
Jan 16 2023	Viglione et al., The Gazette of Medical Sciences, doi:10.46766/thegms.pubheal.22120905	Intravenous high dose vitamin C and ozonated saline effective treatment for Covid-19: The Evolution of Local Standard of Care
	Retrospective 479 high risk outpatients in the USA treated with a protocol including intravenous vitamin C, vitamin D, zinc, quercetin, bromelain, lactoferrin, HCQ, ivermectin, ozonated saline, azithromycin, ceftriaxone, methylprednisolon..
Jan 16 2023	Argano et al., Pharmaceuticals, doi:10.3390/ph16010130	Protective Effect of Vitamin D Supplementation on COVID-19-Related Intensive Care Hospitalization and Mortality: Definitive Evidence from Meta-Analysis and Trial Sequential Analysis
	51% lower mortality (p=0.0002) and 72% lower ICU admission (p<0.0001). Meta analysis and trial sequential analysis of 5 vitamin D RCTs, showing significantly lower mortality and ICU admission with treatment. Only a small subset of the RCTs are included. Note that [Nogués] uses randomization by ward, was ce..
Jan 10 2023	Ubaldi et al., Work, doi:10.3233/WOR-220387	Vitamin D status and COVID-19 prevention in a worker subgroup in Italy
	Report on vitamin D supplementation with 139 employees in Italy from April to June 2021, showing only one confirmed COVID-19 case (0.7%) and 4 cases of flu-like symptoms, compared to ~7-9% COVID-19 incidence for the same Italian district ..
Dec 31 2022	Şengül et al., Cukurova Anestezi ve Cerrahi Bilimler Dergisi, doi:10.36516/jocass.1185181	Serum Vitamin D Concentrations and Covid-19 In Pregnant Women, Does Vitamin D Supplementation Impact Results? A Comprehensive Study
	69% fewer cases (p=0.004). Retrospective 318 pregnant women, 54 COVID+ and 264 healthy controls, showing lower risk of COVID-19 with vitamin D supplementation, and with higher vitamin D levels.
Dec 29 2022	De Nicolò et al., Nutrients, doi:10.3390/nu15010169	Possible Impact of Vitamin D Status and Supplementation on SARS-CoV-2 Infection Risk and COVID-19 Symptoms in a Cohort of Patients with Inflammatory Bowel Disease
	88% lower IgG positivity (p=0.002). Prospective study of 106 IBD patients in Italy, showing lower risk of IgG positivity with vitamin D supplementation. Vitamin D levels below 30 ng/mL were associated with a higher probability of symptomatic cases.
Dec 26 2022	Batur et al., Diagnostics, doi:10.3390/diagnostics13010059	Association between Vitamin D Status and Secondary Infections in Patients with Severe COVID-19 Admitted in the Intensive Care Unit of a Tertiary-Level Hospital in Turkey
	72% lower mortality (p<0.0001) and 23% improvement (p=0.03). Retrospective 194 ICU patients and 30 non-COVID-19 patients in Turkey, showing significantly lower vitamin D levels in COVID-19 patients. There was significantly higher COVID-19 mortality with vitamin D deficiency, and significantly highe..
Dec 25 2022	Qu et al., arXiv, doi:10.48550/arXiv.2301.02660	Decreased serum vitamin D level as a prognostic marker in patients with COVID-19
	Retrospective 719 COVID-19 patients in China, showing higher vitamin D levels associated with faster viral clearance and lower severity.
Dec 15 2022	Khojah et al., Nutrients, doi:10.3390/nu14245329	The Impact of Serum Levels of Vitamin D3 and Its Metabolites on the Prognosis and Disease Severity of COVID-19
	Analysis of 103 COVID-19 patients and 50 healthy controls in Saudi Arabia, showing significantly lower vitamin D and vitamin D metabolite levels in COVID-19 patients, and correlations between vitamin D levels and ACE2 levels, IL-6, and NL..
Dec 12 2022	Zaazouee et al., Naunyn-Schmiedeberg's Archives of Pharmacology, doi:10.1007/s00210-022-02360-x	Hospital and laboratory outcomes of patients with COVID-19 who received vitamin D supplementation: a systematic review and meta-analysis of randomized controlled trials
	Systematic review and meta-analysis of 9 RCTs (1,586 patients) showing significantly lower ICU admission with vitamin D treatment for COVID-19. There was no significant difference for other outcomes.
Dec 8 2022	Ali et al., Asian Journal of Research in Biochemistry, doi:10.9734/ajrb/2022/v11i2214	Vitamin D, Calcium and Phosphorus Status Involvement during COVID-19 Infection
	Retrospective 50 hospitalized COVID-19 patients and 50 healthy controls, showing lower vitamin D levels in COVID-19 patients, and a negative correlation between vitamin D level and COVID-19 severity.
Dec 7 2022	Baxter et al., Nutrients, doi:10.3390/nu14245204	Correlation between 25-hydroxyvitamin D/D3 Deficiency and COVID-19 Disease Severity in Adults from Northern Colorado
	Analysis of 131 COVID+ patients and 18 healthy controls, showing COVID-19 severity associated with lower vitamin D levels.
Dec 5 2022	Abdrabbo AlYafei et al., Qatar Medical Journal, doi:10.5339/qmj.2022.48	Association of Serum Vitamin D level and COVID-19 infection: A Case-control Study
	23% fewer cases (p<0.0001). Retrospective 16,446 COVID-19 patients and 46,005 healthy controls in Qatar, showing higher risk of COVID-19 infection with vitamin D deficiency.
Dec 2 2022	Vásquez-Procopio et al., International Journal of Molecular Sciences, doi:10.3390/ijms232315188	Association between 25-OH Vitamin D Deficiency and COVID-19 Severity in Pregnant Women
	83% lower severe cases (p=0.04). Retrospective 165 pregnant women in Mexico, showing increased risk of severe COVID-19 with vitamin D deficiency.
Nov 30 2022	Mostafa et al., International Journal of General Medicine, doi:10.2147/IJGM.S386815	Clinical and Prognostic Significance of Baseline Serum Vitamin D Levels in Hospitalized Egyptian Covid-19 Patients
	93% lower mortality (p<0.0001), 95% lower ventilation (p<0.0001), and 91% lower ICU admission (p<0.0001). Retrospective hospitalized patients in Egypt, showing lower vitamin D levels associated with COVID-19 severity and mortality. Adjusted results are only provided for vitamin D as a continuous variable.
Nov 26 2022	Sharif et al., Nutrients, doi:10.3390/nu14235029	Impact of Zinc, Vitamins C and D on Disease Prognosis among Patients with COVID-19 in Bangladesh: A Cross-Sectional Study
	28% lower severe cases (p=0.001). Retrospective 962 COVID-19 patients in Bangladesh, showing significantly lower severity with vitamin C, vitamin D, and zinc supplementation, and improved results from the combination of all three. Table 2 has a typographical error where t..
Nov 18 2022	Nicoll et al., Journal of Clinical Medicine, doi:10.3390/jcm11226818	COVID-19 Prevention: Vitamin D Is Still a Valid Remedy
	Discussion of limitations and concerns for [Jolliffe]
Nov 16 2022	Guldemir et al., Work, doi:10.3233/wor-220292	Clinical characteristics of bus drivers and field officers infected with COVID-19: A cross-sectional study from Istanbul
	5% lower hospitalization (p=0.89). Retrospective 477 COVID+ public transportation workers in Turkey, showing no significant difference in hospitalization with vitamin D use in unadjusted results.
Nov 15 2022	Tallon et al., Diabetes Research and Clinical Practice, doi:10.1016/j.diabres.2022.110156	Impact of diabetes status and related factors on COVID-19-associated hospitalization: A nationwide retrospective cohort study of 116,370 adults with SARS-CoV-2 infection
	42% lower hospitalization (p<0.0001). Retrospective 116,370 COVID+ patients in the USA, showing higher risk of hospitalization with vitamin D deficiency/insufficiency.
Nov 12 2022	Gibbons et al., Scientific Reports, doi:10.1038/s41598-022-24053-4	Association between vitamin D supplementation and COVID-19 infection and mortality
	33% lower mortality (p<0.0001) and 20% fewer cases (p<0.0001). PSM retrospective in the USA, showing lower COVID-19 mortality and cases with vitamin D prophylaxis.
Nov 8 2022	Allami et al., 1st Samarra International Conference for Pure and Applied Sciences (SICPS2021), doi:10.1063/5.0121166	The risk of up normal values of two parameters obesity and vitamin D in incidence of coronavirus disease-19 among Iraqi patients
	93% lower hospitalization (p<0.0001). Retrospective 86 COVID-19 hospitalized patients and 86 healthy controls in Iraq, showing COVID-19 cases associated with severe vitamin D deficiency.
Nov 8 2022	Khalil et al., 1st Samarra International Conference for Pure and Applied Sciences (SICPS2021), doi:10.1063/5.0122108	Evaluation of vitamin D in COVID-19 patients
	42% fewer cases (p=0.27). Case control study with 52 COVID-19 patients and 30 matched controls, showing significantly lower vitamin D levels in COVID-19 patients.
Nov 8 2022	Said et al., Frontiers in Pharmacology, doi:10.3389/fphar.2022.1011522	The effect of Nigella sativa and vitamin D3 supplementation on the clinical outcome in COVID-19 patients: A randomized controlled clinical trial
	42% improved recovery (p=0.57) and 49% improved viral clearance (p=0.2). 120 patient RCT comparing vitamin D, nigella sativa, and combined vitamin D+nigella sativa, showing improved symptom recovery and viral clearance with both vitamin D and nigella sativa, and further improvements with the combination of bot..
Nov 7 2022	Green et al., European Journal of General Practice, doi:10.1080/13814788.2022.2138855	A higher frequency of physical activity is associated with reduced rates of SARS-CoV-2 infection
	19% fewer cases (p<0.0001). Retrospective 113,075 people in Israel, showing lower risk of COVID-19 cases with higher vitamin D levels.
Nov 3 2022	Bychinin et al., Scientific Reports, doi:10.1038/s41598-022-22045-y	Effect of vitamin D3 supplementation on cellular immunity and inflammatory markers in COVID-19 patients admitted to the ICU
	27% lower mortality (p=0.18), 7% lower ventilation (p=0.68), 94% longer ICU admission (p=0.001), and 41% longer hospitalization (p=0.007). RCT ICU patients in Russia, showing significantly increased lymphocyte counts with treatment. Mortality was lower but without statistical significance. 40% of patients were on mechanical ventilation at baseline in the treatment group, com..
Oct 28 2022	Álvarez et al., bioRxiv, doi:10.1101/2022.10.27.514012	Vitamin D deficiency and SARS-CoV-2 infection: Big-data analysis from March 2020 to March 2021. D-COVID study
	39% lower mortality (p<0.0001), 55% lower ICU admission (p<0.0001), and 43% lower hospitalization (p<0.0001). Retrospective free-text analysis of 143,157 COVID-19 patients, showing vitamin D deficiency associated with mortality, ICU admission, and hospitalization in unadjusted results.
Oct 22 2022	Hafezi et al., Scientific Reports, doi:10.1038/s41598-022-22307-9	Vitamin D enhances type I IFN signaling in COVID-19 patients
	63% lower mortality (p=0.04). Retrospective 80 ICU patients, and in vitro study with human airway epithelial cells, showing that vitamin D enhances host IFN-a/β signaling. Significantly lower mortality was seen with vitamin D treatment.
Oct 18 2022	Cosentino et al., Journal of Clinical Medicine, doi:10.3390/jcm11206138	Early Outpatient Treatment of COVID-19: A Retrospective Analysis of 392 Cases in Italy
	Retrospective 392 outpatients in Italy showing 0.2% mortality with early treatment, compared with >3% in Italy at the time. Treatment varied for individual patients and included HCQ, vitamin D, vitamin C, vitamin A, zinc, quercetin, bromh..
Oct 7 2022	Morad et al., Egyptian Rheumatology and Rehabilitation, doi:10.1186/s43166-022-00155-9	Serum vitamin D level in COVID-19 patients and its correlation with disease severity
	Retrospective 80 COVID-19 patients in Egypt, showing lower vitamin D levels associated with mechanical ventilation and mortality.
Oct 3 2022	Karimpour-Razkenari et al., Journal of Pharmaceutical Care, doi:10.18502/jpc.v10i3.10790	Evaluating the Effects of Clinical Characteristics and Therapeutic Regimens on Mortality in Hospitalized Patients with Severe COVID-19
	79% lower mortality (p<0.0001). Retrospective 478 moderate to severe hospitalized patients in Iran, showing lower mortality with vitamin D treatment.
Sep 30 2022	Ahmeid et al., Eurasian Chemical Communications, doi:10.22034/ecc.2023.158071	Evaluating the level of vitamin D in Iraqi COVID-19 patients besides the study of its association with biochemical parameters
	Retrospective 90 COVID-19 patients in Iraq showing significantly lower vitamin D levels in severe cases compared to non-severe cases. Vitamin D levels were negatively correlated with D-dimer, ferritin, and CRP levels.
Sep 27 2022	Sarhan et al., Medicina, doi:10.3390/medicina58101358	Evidence for the Efficacy of a High Dose of Vitamin D on the Hyperinflammation State in Moderate-to-Severe COVID-19 Patients: A Randomized Clinical Trial
	19% lower mortality (p=0.003), 74% greater improvement (p=0.03), and 31% shorter hospitalization (p=0.04). RCT comparing 200,000IU IM cholecalciferol and 1mcg/day alfacalcidol, showing lower mortality and improved recovery with high dose treatment.
Sep 24 2022	Mansour et al., The Egyptian Journal of Internal Medicine, doi:10.1186/s43162-022-00159-z	Association of serum zinc level and clinical outcome in Egyptian COVID-19 patients
	Retrospective 30 ICU patients and 30 non-ICU hospitalized patients in Egypt, showing lower vitamin D levels in ICU patients.
Sep 19 2022	Mosadegh et al., Microbial Pathogenesis, doi:10.1016/j.micpath.2022.105792	The effect of Nutrition Bio-shield superfood (NBS) on disease severity and laboratory biomarkers in patients with COVID-19: A randomized clinical trial
	61% lower mortality (p=0.002) and 28% shorter hospitalization (p=0.001). RCT 70 hospitalized severe COVID-19 patients in Iran, showing lower mortality and improved clinical markers with treatment combining vitamins A, B1-B3, B5, B6, B9, C, D, K, and magnesium, potassium, phosphorus, sulfur, manganese, calcium,..
Sep 17 2022	van Helmond et al., Nutrients, doi:10.3390/nu15010180 (date from preprint)	Vitamin D3 Supplementation at 5000 IU Daily for the Prevention of Influenza-like Illness in Healthcare Workers: A Pragmatic Randomized Clinical Trial
	98% fewer cases (p=0.07). Prospective prophylaxis trial with 255 healthcare workers taking vitamin D and 2,827 controls, showing significantly lower influenza-like illness with treatment, and lower COVID-19 cases, without statistical significance. While the interv..
Sep 12 2022	Szerszeń et al., Medical Science Monitor, doi:10.12659/MSM.937741	Effect of Vitamin D Concentration on Course of COVID-19
	Retrospective 505 hospitalized patients in Poland, showing low vitamin D levels associated with oxygen therapy and ventilation. There was no significant difference for cases.
Sep 9 2022	Zeidan et al., Pediatric Research, doi:10.1038/s41390-022-02275-6	Vitamin D deficiency and vitamin D receptor FokI polymorphism as risk factors for COVID-19
	62% lower hospitalization (p=0.002). Prospective study of 180 moderate to critical hospitalized pediatric COVID-19 patients and 200 matched controls, showing vitamin D deficiency and the VDR Fok I polymorphism associated with COVID-19 hospitalization.
Sep 7 2022	Brunvoll et al., BMJ, doi:10.1136/bmj-2022-071245	Prevention of covid-19 and other acute respiratory infections with cod liver oil supplementation, a low dose vitamin D supplement: quadruple blinded, randomised placebo controlled trial
	11% lower hospitalization (p=1), 20% higher severe cases (p=0.17), and no change in cases (p=0.98). RCT 17,278 low-risk patients (zero mortality) treated with 5mL/day cod liver oil (~400IU vitamin D) and 17,323 placebo patients in Norway, showing no significant differences with treatment. The placebo group had higher vitamin D at baseli..
Sep 2 2022	Foshati et al., Food Science & Nutrition, doi:10.1002/fsn3.3034	Antioxidants and clinical outcomes of patients with coronavirus disease 2019: A systematic review of observational and interventional studies
	Systematic review showing that vitamin C, vitamin D, selenium, and zinc can improve COVID-19 clinical outcomes.
Aug 24 2022	Saheb Sharif-Askari et al., Life Sciences, doi:10.1016/j.lfs.2022.120909	Vitamin D modulates systemic inflammation in patients with severe COVID-19
	36% shorter ICU admission (p=0.01). Retrospective 20 ICU patients treated with vitamin D in the UAE, and 25 matched controls, showing significantly shorter ICU stay with treatment. Lower proinflammatory cytokines were associated with lower severity markers. Authors also per..
Aug 18 2022	Gkioulekas et al., COVID, doi:10.3390/covid2080084	Statistical Analysis Methods Applied to Early Outpatient COVID-19 Treatment Case Series Data
	Retrospective analysis of case series data from 3,164 high-risk COVID-19 outpatients treated with early multidrug protocols similar to the McCullough protocol, including hydroxychloroquine, ivermectin, zinc, azithromycin, vitamin C, vitam..
Aug 15 2022	Sinnberg et al., Antioxidants, doi:10.3390/antiox11081580	Vitamin C Deficiency in Blood Samples of COVID-19 Patients
	Analysis of 74 COVID-19 patients and 8 controls in Germany, showing low vitamin C levels associated with mortality. There was no significant difference for vitamin A, D, or E levels. Very few group details are provided, for example the ag..
Aug 12 2022	Shannak et al., Technium BioChemMed, doi:10.47577/biochemmed.v3i2.7179	Evaluation of the level of vitamin D3 in the blood serum of patients infected with COVID-19 in Al-Amiriya city
	Analysis of 35 COVID-19 patients and 25 healthy controls in Iraq, showing significantly lower vitamin D levels in COVID-19 patients.
Aug 11 2022	Dana et al., The Eurasian Journal of Medicine, doi:10.5152/eurasianjmed.2022.21088	Vitamin D Level in Laboratory Confirmed COVID-19 and Disease Progression
	33% lower mortality (p=0.29) and no change in severe cases (p=1). Analysis of 831 hospitalized patients in Iran, showing higher mortality with severe vitamin D deficiency, without statistical significance.
Aug 10 2022	Chellasamy et al., Journal of King Saud University - Science, doi:10.1016/j.jksus.2022.102277	Docking and molecular dynamics studies of human ezrin protein with a modelled SARS-CoV-2 endodomain and their interaction with potential invasion inhibitors
	In silico study of SARS-CoV-1&2 endodomains and ezrin docking, identifying ivermectin, quercetin, calcifediol, calcitriol, selamectin, and minocycline as potential therapeutic drugs with strong ezrin binding which may restrict viral endod..
Aug 9 2022	Hafez et al., Antibiotics, doi:10.3390/antibiotics11081078	Factors Influencing Disease Stability and Response to Tocilizumab Therapy in Severe COVID-19: A Retrospective Cohort Study
	94% lower mortality (p=0.07). Retrospective 49 severe COVID-19 patients treated with tocilizumab, showing lower mortality with vitamin D treatment and a dose-dependent response.
Aug 9 2022	Barrett et al., Nutrients, doi:10.3390/nu14163252	Vitamin D Status and Mortality from SARS CoV-2: A Prospective Study of Unvaccinated Caucasian Adults
	78% lower mortality (p=0.006), 15% lower ICU admission (p=0.63), and 53% lower progression (p=0.12). Prospective study of 232 hospitalized COVID-19 pneumonia patients, showing higher risk of mortality with vitamin D deficiency.
Aug 4 2022	Doğan et al., Journal of Tropical Pediatrics, doi:10.1093/tropej/fmac072	The Clinical Significance of Vitamin D and Zinc Levels with Respect to Immune Response in COVID-19 Positive Children
	64% fewer cases (p=0.003). Prospective study of 88 pediatric COVID-19 patients and 88 healthy controls, showing significantly lower zinc and vitamin D levels in COVID-19 patients.
Jul 31 2022	Alarslan et al., Medical Journal of İzmir Hospital, 26:3	Vitamin D levels and disease severity in COVID-19
	Retrospective 153 COVID-19 patients in Turkey, showing lower age-adjusted vitamin D levels in hospitalized patients vs. outpatients.
Jul 31 2022	Mishra et al., Journal of Preventive Medicine and Public Health, doi:10.3961/jpmph.21.640	Vitamin D Deficiency and Comorbidities as Risk Factors of COVID-19 Infection: A Systematic Review and Meta-analysis
	Systematic review and meta analysis showing low vitamin D levels associated with COVID-19 cases.
Jul 27 2022	Lakkireddy et al., Archives of Clinical and Biomedical Research, doi:10.26502/acbr.50170273	Effect of Short Term High Dose Oral Vitamin D Therapy on the Inflammatory Markers in Patients with COVID 19 Disease
	61% lower mortality (p=0.27), 22% lower ICU admission (p=0.74), and 7% shorter hospitalization (p=0.9). RCT 44 treatment and 43 control patients with vitamin D levels <30ng/ml, showing significant reduction in inflammatory markers with treatment of 60,000IU vitamin D per day for 8 days (10 days for BMI >25). Death and ICU admission was lowe..
Jul 26 2022	Fairfield et al., Nutrients, doi:10.3390/nu14153073	Association of Vitamin D Prescribing and Clinical Outcomes in Adults Hospitalized with COVID-19
	9% higher mortality (p<0.0001) and 41% higher ventilation (p<0.0001). N3C retrospective showing higher risk with vitamin D treatment for hospitalized patients. As noted by authors, confounding by indication may be significant. The more extreme ventilation result, which is a significant outlier among all stu..
Jul 26 2022	De Niet et al., Nutrients, doi:10.3390/nu14153048	Positive Effects of Vitamin D Supplementation in Patients Hospitalized for COVID-19: A Randomized, Double-Blind, Placebo-Controlled Trial
	45% faster recovery (p=0.06) and 50% shorter hospitalization (p=0.003). RCT with 21 vitamin D and 22 placebo hospitalized patients in Belgium with vitamin D deficiency, showing significantly shorter hospitalization and improved clinical recovery with treatment.
Jul 25 2022	Peng et al., Frontiers in Nutrition, doi:10.3389/fnut.2022.960859	Vitamin D levels and clinical outcomes of SARS-CoV-2 Omicron subvariant BA.2 in children: A longitudinal cohort study
	Retrospective 116 hospitalized pediatric patients in China, showing accelerated viral clearance early in the disease course, and greater pneumonia lesion improvement with vitamin D sufficiency.
Jul 25 2022	Zurita-Cruz et al., Frontiers in Pediatrics, doi:10.3389/fped.2022.943529	Efficacy and safety of vitamin D supplementation in hospitalized COVID-19 pediatric patients: A randomized controlled trial
	79% lower mortality (p=0.11), 72% lower ventilation (p=0.08), and 73% lower ICU admission (p=0.006). RCT 45 hospitalized high-risk pediatric patients requiring supplemental oxygen in Mexico, showing lower mortality, ventilation, and intensive care with vitamin D treatment, however there were less severe and critical cases at baseline in ..
Jul 21 2022	Abroug et al., Trials, doi:10.1186/s13063-023-07114-5	Effect of vitamin D supplementation versus placebo on recovery delay among COVID-19 Tunisian patients: a randomized-controlled clinical trial
	8% improved recovery (p=0.85) and 58% worse viral clearance (p=0.02). Long COVID RCT with mostly asymptomatic patients that remained PCR positive for 14 days, showing slower viral conversion with treatment. Authors report "a 30-day follow-up of our patients showed that a long-lasting COVID-19 was no..
Jul 19 2022	Gholi et al., Complementary Therapies in Medicine, doi:10.1016/j.ctim.2022.102855	Vitamin D deficiency is associated with increased risk of delirium and mortality among critically Ill, elderly covid-19 patients
	75% lower mortality (p=0.0007) and 45% higher ventilation (p=0.27). Prospective study of 310 COVID-19 ICU patients in Iran, showing higher mortality for patients with vitamin D deficiency.
Jul 19 2022	Hosseini et al., Research Square, doi:10.21203/rs.3.rs-1588325/v1	PRevention of COVID-19 with Oral Vitamin D supplemental Therapy in Essential healthCare Teams (PROTECT): Ancillary study of a randomised controlled trial
	82% fewer cases (p=0.19). Early terminated prophylaxis RCT for healthcare workers in Canada, showing 0/19 cases with vitamin D prophylaxis vs. 2/15 for control. 100,000IU cholecalciferol at baseline, 10,000IU weekly for 16 weeks.
Jul 15 2022	Romero-Ibarguengoitia et al., medRxiv, doi:10.1101/2022.07.12.22277450	Effect of Vitamin D3 supplementation vs. dietary-hygienic measures on SARS-COV-2 infection rates in hospital workers with 25-hydroxyvitamin D3 [25(OH)D3] levels >20 ng/mL
	79% fewer cases (p=0.008). RCT healthcare workers with vitamin D levels between 20-100 ng/mL, 43 treated with vitamin D 52,000 IU monthly, and 42 with dietary-hygienic measures, which were also focused on increasing vitamin D, including sun exposure for at least 10..
Jul 13 2022	Charla et al., Research Square, doi:10.21203/rs.3.rs-1826271/v1	Is suboptimal circulating level of vitamin D a risk factor for the poor prognosis of COVID-19? – A comparison of first and second waves in India
	11% lower mortality (p=0.74). Retrospective 179 hospitalized COVID-19 patients in India, showing no significant difference in mortality with vitamin D deficiency in unadjusted results. Patients with deficiency were younger.
Jul 6 2022	D’Ecclesiis et al., PLOS ONE, doi:10.1371/journal.pone.0268396	Vitamin D and SARS-CoV2 infection, severity and mortality: A systematic review and meta-analysis
	65% lower mortality (p=0.004) and 62% lower severe cases (p=0.003). Systematic review showing significantly lower risk of mortality and severe cases with vitamin D supplementation, and for high vs. low vitamin D levels.
Jul 6 2022	Mamurova et al., Research Square, doi:10.21203/rs.3.rs-1806260/v1	A strong association between the VDR gene markers and SARS-CoV-2 variants
	Analysis of 300 PCR+ and 300 PCR- patients, showing COVID-19 associated with vitamin D receptor polymorphisms FokI and TaqI. Notably, these polymorphisms have been found to be associated with improved response to vitamin D supplementation..
Jul 5 2022	Bogliolo et al., Frontiers in Nutrition, doi:10.3389/fnut.2022.934258	Vitamin D 25OH Deficiency and Mortality in Moderate to Severe COVID-19: A Multi-Center Prospective Observational Study
	15% lower mortality (p=0.29). Prospective 361 consecutive hospitalized patients in Italy, showing 77% had vitamin D deficiency. There was no statistically significant difference in mortality with deficiency.
Jul 4 2022	Cervero et al., Frontiers in Pharmacology, doi:10.3389/fphar.2022.863587	Beneficial Effect of Short-Term Supplementation of High Dose of Vitamin D3 in Hospitalized Patients With COVID-19: A Multicenter, Single-Blinded, Prospective Randomized Pilot Clinical Trial
	79% lower ICU admission (p=0.2) and 28% lower ARDS (p=0.74). RCT 85 hospitalized patients in Spain, comparing 10,000IU/day vs. 2,000IU/day cholecalciferol, showing beneficial effects of the larger dose.
Jul 2 2022	Gupta et al., Nutrients, doi:10.3390/nu14132757	Temporal Association of Reduced Serum Vitamin D with COVID-19 Infection: Two Single-Institution Case–Control Studies
	Retrospective study of 107 COVID-19 patients with vitamin D levels measured within 180 days before diagnosis, and 203 patients with levels measured after diagnosis, showing lower vitamin D levels for COVID-19 hospitalized patients compare..
Jun 30 2022	Borzouei et al., Nutrition and Food Sciences Research, 9:2	Assessment of Vitamin D, Vitamin B12, Retinol-binding Protein (RBP), Zinc, Selenium, Copper and Magnesium in Iranian COVID-19 Patients and Their Relationships with the Disease Linked Death
	Analysis of 98 hospitalized COVID-19 patients showing that a high proportion of patients had nutrient deficiencies: 59% for vitamin D, 12% for vitamin B12, 53% for RBP, 31% for zinc, 89% for selenium, 16% for copper, and 27% for magnesium..
Jun 29 2022	Quesada-Gomez et al., Nutrients, doi:10.3390/nu14132716	Vitamin D Endocrine System and COVID-19: Treatment with Calcifediol
	Review of the use of calcifediol for COVID-19. Authors note several advantages of calcifediol vs. cholecalciferol: calcifediol induces a more rapid increase in circulating 250HD; calcifediol is more potent than cholecalciferol; calcifedio..
Jun 29 2022	Hunt et al., Journal of General Internal Medicine, doi:10.1007/s11606-022-07701-3	Medications Associated with Lower Mortality in a SARS-CoV-2 Positive Cohort of 26,508 Veterans
	47% lower mortality (p=0.0007). Retrospective 26,508 consecutive COVID+ veterans in the USA, showing lower mortality with multiple treatments including vitamin D. Treatment was defined as drugs administered ≥50% of the time within 2 weeks post-COVID+, and may be a conti..
Jun 26 2022	Nicolescu et al., Farmacia, doi:10.31925/farmacia.2022.3.17	The evaluation of vitamin D deficiency as a risk factor in the case of patients with moderate COVID-19
	Retrospective 128 hospitalized patients in Romania, showing a negative outcome associated with lower vitamin D levels.
Jun 23 2022	Alzahrani et al., Cureus, doi:10.7759/cureus.26266	The Association Between Vitamin D Serum Level and COVID-19 Patients’ Outcomes in a Tertiary Center in Saudi Arabia: A Retrospective Cohort Study
	43% lower mortality (p=0.46) and 7% lower ICU admission (p=0.8). Retrospective 545 hospitalized patients in Saudi Arabia, showing higher mortality with vitamin D deficiency, without statistical significance.
Jun 23 2022	Karonova et al., Nutrients, doi:10.3390/nu14132602	Effect of Cholecalciferol Supplementation on the Clinical Features and Inflammatory Markers in Hospitalized COVID-19 Patients: A Randomized, Open-Label, Single-Center Study
	86% lower ICU admission (p=0.11) and 7% lower need for oxygen therapy (p=0.85). RCT with 56 cholecalciferol and 54 control hospitalized patients with vitamin D insufficiency or deficiency in Russia, showing positive effects on immune status. The median age in the treatment group was 7 years lower and deficiency was l..
Jun 17 2022	Shahid et al., Abstracts from the 2022 Annual Meeting of the Society of General Internal Medicine, Journal of General Internal Medicine, doi:10.1007/s11606-022-07653-8	The effects of vitamin D therapy on outcomes for hispanic patients hospitalized for COVID-19
	38% lower mortality (p=0.001). Retrospective 1,478 hospitalized Hispanic patients in the USA with 705 receiving vitamin D treatment, showing lower mortality with treatment in unadjusted results. Very minimal information is currently available.
Jun 14 2022	Neves et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2022.05.027	Vitamin D deficiency predicts 30-day hospital mortality of adults with COVID-19
	57% lower mortality (p=0.05) and 20% higher ICU admission (p=0.81). Retrospective 115 hospitalized patients in Brazil, showing lower mortality with higher vitamin D levels. Adjusted results are only provided for vitamin D as a continuous variable.
Jun 1 2022	Singh et al., Journal of Public Health, doi:10.1093/pubmed/fdae007 (conference publication 6/1/2022)	Therapeutic high-dose vitamin D for vitamin D-deficient severe COVID-19 disease: randomized, double-blind, placebo-controlled study (SHADE-S)
	45% lower mortality (p=0.05) and 40% improved recovery (p=0.01). RCT 90 vitamin D deficient moderate/severe COVID-19 ARDS patients in India, showing lower mortality with vitamin D treatment. 600,000IU nanoformulation cholecalciferol.
May 31 2022	Annweiler et al., PLoS Medicine, doi:10.1371/journal.pmed.1003999	High-dose versus standard-dose vitamin D supplementation in older adults with COVID-19 (COVIT-TRIAL): A multicenter, open-label, randomized controlled superiority trial
	30% lower mortality (p=0.29). RCT comparing single dose 400,000IU and single dose 50,000IU vitamin D in France, showing lower mortality with the higher dose, statistically significant only at day 14. The aHR for days 0-5 was 1.30 [0.31-5.35], compared to 0.11 [0.02-0...
May 30 2022	Baykal et al., Journal of Health Sciences and Medicine, doi:10.32322/jhsm.1063405	Correlation of vitamin D level with the clinical-radiological severity of COVID-19 in geriatric patients
	22% lower mortality (p=0.43) and 59% lower ICU admission (p=0.005). Retrospective 75 patients in Turkey showing lower ICU admission with vitamin D treatment in unadjusted results subject to confounding by time and indication (treatment was given to patients with low levels and only during a certain period..
May 30 2022	Kumar et al., Cureus, doi:10.7759/cureus.25467	Efficacy and Safety of Aspirin, Promethazine, and Micronutrients for Rapid Clinical Recovery in Mild to Moderate COVID-19 Patients: A Randomized Controlled Clinical Trial
	57% improved recovery (p=0.25). RCT 260 patients in India, 130 treated with aspirin, promethazine, vitamin C, D, B3, zinc, and selenium, showing faster recovery with treatment. There was no hospitalization, ICU admission, or supplemental oxygen requirements in either gr..
May 27 2022	Galmés et al., Nutrients, doi:10.3390/nu14112254	Suboptimal Consumption of Relevant Immune System Micronutrients Is Associated with a Worse Impact of COVID-19 in Spanish Populations
	Ecological study in Spain, showing lower intake of vitamin D, A, B9, and zinc in regions with the highest COVID-19 incidence and mortality. Vitamin D intake was associated with lower prevalence, incidence, and a combined incidence+mortali..
May 27 2022	Mariani et al., PLOS ONE, doi:10.1371/journal.pone.0267918	High-dose vitamin D versus placebo to prevent complications in COVID-19 patients: Multicentre randomized controlled clinical trial
	25% lower ventilation (p=0.85), 27% lower ICU admission (p=0.62), and 3% lower progression (p=0.82). Late stage RCT with 115 patients treated with a single dose of 500,000IU cholecalciferol and 103 placebo patients, showing no significant differences. Authors do not explain why they did very late treatment with cholecalciferol instead of..
May 22 2022	Fiore et al., Healthcare, doi:10.3390/healthcare10050956	Effectiveness of Vitamin D Supplements among Patients Hospitalized for COVID-19: Results from a Monocentric Matched-Cohort Study
	93% lower mortality (p=0.02), 50% lower ventilation (p=0.36), 50% lower ICU admission (p=0.36), and 48% lower progression (p=0.04). Retrospective 116 patients with D levels < 30ng/mL, 58 treated with vitamin D 100,000IU daily for two days, and 58 matched controls, showing significantly lower mortality with treatment.
May 20 2022	Hosseini et al., Nutrients, doi:10.3390/nu14102134	Effects of Vitamin D Supplementation on COVID-19 Related Outcomes: A Systematic Review and Meta-Analysis
	54% lower mortality (p=0.0004), 65% lower ICU admission (p=0.0003), and 9% fewer cases (p=0.11). Systematic review and meta analysis showing significantly lower ICU admission and mortality with vitamin D treatment. There was no significant difference for cases.
May 16 2022	Ozturk et al., Bratislava Medical Journal, doi:10.4149/BLL_2022_065	Is there a relationship between vitamin D levels, inflammatory parameters, and clinical severity of COVID-19 infection?
	46% lower severe cases (p=0.1). Retrospective 300 hospitalized patients in Turkey with vitamin D levels measured with 6 months before admission, showing no significant difference in severity based on vitamin D deficiency.
May 13 2022	Zangeneh et al., Obesity Medicine, doi:10.1016/j.obmed.2022.100420	Survival analysis based on body mass index in patients with Covid-19 admitted to the intensive care unit of Amir Al-Momenin Hospital in Arak – 2021
	26% higher mortality (p=0.4). Retrospective 193 ICU patients in Iran, showing no significant difference with vitamin D treatment. This study has multiple data issues: The text states that 134 people died and 59 were discharged. However, in Table 1, the column labeled ..
May 13 2022	Galluzzo et al., Mechanisms of Ageing and Development, doi:10.1016/j.mad.2022.111684	Association between vitamin D status and physical performance in COVID-19 survivors: Results from the Gemelli against COVID-19 post-acute care project
	Analysis of 681 COVID-19 survivors in Italy, showing a high prevalence of vitamin D deficiency. Low vitamin D levels were associated with poor physical performance, and were more common in patients that had been hospitalized.
May 11 2022	Jabeen et al., Pakistan Journal of Medical and Health Sciences, doi:10.53350/pjmhs221631053	Protective Effect of Vitamin-D Supplementation in Patients of Acute Coronary Syndrome During COVID-19 Pandemic
	89% fewer symptomatic cases (p=0.11). Prospective study of 40 acute coronary syndrome patients in Pakistan, 20 given a single dose of 200,000IU vitamin D, showing lower incidence of COVID-19 in the following 2 months.
May 7 2022	Kazemi et al., BMC Infectious Diseases, doi:10.1186/s12879-022-07438-8	Comparison of the cardiovascular system, clinical condition, and laboratory results in COVID-19 patients with and without vitamin D insufficiency
	76% lower mortality (p=0.26) and 5% higher severe cases (p=1). Retrospective 202 hospitalized COVID-19 patients in Iran, showing no significant difference in outcomes based on vitamin D levels.
May 5 2022	Charkowick et al., AJRCCM Conference, 205:A4571	Vitamin D Deficiency and Thrombosis in Hospitalized SARS-CoV-2 Patients with Suspected Pulmonary Embolism
	73% lower mortality (p=0.02) and 67% lower ICU admission (p=0.001). Retrospective 208 hospitalized COVID+ patients in the USA, showing vitamin D deficiency associated with higher mortality and ICU admission.
May 3 2022	Nguyen et al., PLOS ONE, doi:10.1371/journal.pone.0268038	25-hydroxyvitamin D is a predictor of COVID-19 severity of hospitalized patients
	81% lower mortality (p=0.008), 53% lower ventilation (p=0.13), and 74% higher hospital discharge (p<0.0001). Retrospective 88 COVID-19 hospitalized patients and 122 controls, showing higher mortality, ventilation, and length of stay with vitamin D deficiency.
May 1 2022	Khan et al., Frontiers in Pharmacology, doi:10.3389/fphar.2022.898062	Oral Co-Supplementation of Curcumin, Quercetin, and Vitamin D3 as an Adjuvant Therapy for Mild to Moderate Symptoms of COVID-19—Results From a Pilot Open-Label, Randomized Controlled Trial
	33% improved recovery (p=0.15) and 50% improved viral clearance (p=0.009). RCT 50 COVID+ outpatients in Pakistan, 25 treated with curcumin, quercetin, and vitamin D, showing significantly faster viral clearance, significantly improved CRP, and faster resolution of acute symptoms (p=0.154). 168mg curcumin, 260mg ..
Apr 30 2022	Voelkle et al., Nutrients, doi:10.3390/nu14091862	Prevalence of Micronutrient Deficiencies in Patients Hospitalized with COVID-19: An Observational Cohort Study
	23% lower combined mortality/ICU admission (p=0.55). Prospective study of 57 consecutive hospitalized COVID-19 patients in Switzerland, showing higher risk of mortality/ICU admission with vitamin A, vitamin D, and zinc deficiency, with statistical significance only for vitamin A and zinc. A..
Apr 26 2022	Valecha et al., International Journal of Pharmaceutical and Clinical Research, 14:5	The Effect of Vitamin B12, Magnesium and Vitamin D in COVID-19 among Geriatric Patients
	87% lower ICU admission (p=0.09) and 38% shorter hospitalization (p<0.0001). Prospective study of 30 patients treated with vitamin D, magnesium, and vitamin B12, and 25 control patients, showing shorter hospitalization and lower oxygen and ICU requirements with treatment. Cholecalciferol 1000IU, magnesium oxide 15..
Apr 26 2022	Kalichuran et al., Southern African Journal of Infectious Diseases, doi:10.4102/sajid.v37i1.359	Vitamin D status and COVID-19 severity
	60% fewer symptomatic cases (p<0.0001). Prospective study of 100 COVID-19 patients in South Africa, 50 with COVID-19 pneumonia and 50 asymptomatic, showing higher risk of symptomatic COVID-19 with vitamin D deficiency and with lower exposure to sunlight. Authors analyzed sunlig..
Apr 20 2022	Pandya et al., Informatics in Medicine Unlocked, doi:10.1016/j.imu.2022.100951	Unravelling Vitamin B12 as a potential inhibitor against SARS-CoV-2: A computational approach
	In silico study showing significant interaction with SARS-CoV-2 targets for multiple vitamins.
Apr 20 2022	Karimian et al., European Journal of Translational Myology, doi:10.4081/ejtm.2022.10453	Association of vitamin D and severity of COVID-19 in children
	Analysis of 99 pediatric COVID-19 cases in Iran, mean age 2.9, showing severity associated with vitamin D levels.
Apr 18 2022	Villasis-Keever et al., Archives of Medical Research, doi:10.1016/j.arcmed.2022.04.003	Efficacy and Safety of Vitamin D Supplementation to Prevent COVID-19 in Frontline Healthcare Workers. A Randomized Clinical Trial
	78% fewer cases (p=0.001). RCT 321 healthcare workers in Mexico, showing significantly lower SARS-CoV-2 infection with vitamin D prophylaxis. 4,000IU daily for 30 days. In comparison to [Jolliffe], this study used a higher dose, the participants had much higher ex..
Apr 14 2022	Torres et al., Biomedicine & Pharmacotherapy, doi:10.1016/j.biopha.2022.112965	Changes in the immune response against SARS-CoV-2 in individuals with severe COVID-19 treated with high dose of vitamin D
	28% lower ARDS (p=0.74) and 31% shorter hospitalization. RCT comparing 41 patients treated with 10,000IU/day cholecalciferol and 44 treated with 2,000IU/day in Spain, showing significantly shorter hospitalization for ARDS patients with the higher dose. There was also an increase of anti-inflamm..
Apr 14 2022	Parant et al., Nutrients, doi:10.3390/nu14081641	Vitamin D and COVID-19 Severity in Hospitalized Older Patients: Potential Benefit of Prehospital Vitamin D Supplementation
	50% lower mortality (p=0.11), 51% lower ICU admission (p=0.008), and 39% lower severe cases (p=0.01). Retrospective 228 hospitalized COVID-19 patients, median age 78, showing significantly lower risk of ICU admission and severe cases with vitamin D prophylaxis. NCT04877509.
Apr 9 2022	Takase et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2022.04.003	Association between 25-hydroxyvitamin D levels and COVID-19 severity
	Retrospective 117 consecutive COVID+ hospitalized patients in Japan, showing lower vitamin D levels associated with mechanical ventilation or mortality.
Apr 5 2022	Latifi-Pupovci et al., Scientific Reports, doi:10.1038/s41598-022-09785-7	Relationship of anti-SARS-CoV-2 IgG antibodies with Vitamin D and inflammatory markers in COVID-19 patients
	Prospective study of 69 COVID+ patients in Kosovo, showing lower vitamin D levels associated with COVID-19 severity.
Mar 31 2022	Martínez-Rodríguez et al., Gaceta Médica de México, doi:10.24875/GMM.M22000637	Evaluation of the usefulness of vitamin D as a predictor of mortality in patients with COVID-19
	52% lower mortality (p=0.04). Retrospective 154 consecutive COVID-19 patients in Mexico, showing low vitamin D levels associated with higher mortality.
Mar 29 2022	Hafez et al., Frontiers in Medicine, doi:10.3389/fmed.2022.843737	Vitamin D Status in Relation to the Clinical Outcome of Hospitalized COVID-19 Patients
	98% lower mortality (p=0.02). Retrospective 126 hospitalized COVID-19 patients in the UAE, showing vitamin D deficiency associated with mortality.
Mar 26 2022	Ferrer-Sánchez et al., International Journal of Environmental Research and Public Health, doi:10.3390/ijerph19073965	Serum 25(OH) Vitamin D Levels in Pregnant Women with Coronavirus Disease 2019 (COVID-19): A Case-Control Study
	63% fewer cases (p=0.01). Retrospective 256 pregnant women, 82 with COVID-19 and 174 controls, showing significantly lower vitamin D levels for COVID-19 patients.
Mar 23 2022	Ghanei et al., European Journal of Clinical Nutrition, doi:10.1038/s41430-022-01095-5	Low serum levels of zinc and 25-hydroxyvitmain D as potential risk factors for COVID-19 susceptibility: a pilot case-control study
	42% fewer cases (p=0.09). Case control study with 90 COVID-19 cases and 95 matched controls in Iran, showing significantly lower vitamin D levels for cases.
Mar 23 2022	Jolliffe et al., BMJ, doi:10.1136/bmj-2022-071230 (date from preprint)	Effect of a test-and-treat approach to vitamin D supplementation on risk of all cause acute respiratory tract infection and covid-19: phase 3 randomised controlled trial (CORONAVIT)
	41% higher hospitalization (p=0.16) and 9% more cases (p=0.55). RCT 5,979 low risk patients (zero COVID-19 deaths) in the UK, showing no significant differences with vitamin D prophylaxis. 51% of confirmed COVID-19 cases were hospitalized in the control arm which is 7 times the median rate in other st..
Mar 16 2022	Pande et al., Journal of Communicable Diseases, doi:10.24321/0019.5138.202227	Vitamin D Levels and its Association with Inflammatory Markers, Severity and Outcome in Hospitalised COVID-19 Patients - An Indian Perspective
	93% lower severe cases (p<0.0001). Retrospective 209 hospitalized patients in India, showing vitamin D deficiency associated with COVID-19 severity.
Mar 10 2022	DiGuilio et al., International Journal of Molecular Sciences, doi:10.3390/ijms23062995	Micronutrient Improvement of Epithelial Barrier Function in Various Disease States: A Case for Adjuvant Therapy
	Review of epithelial and endothelial barrier compromise and associated disease risk including COVID-19, and the potential benefits of vitamin A, vitamin D, and zinc for improving barrier function.
Mar 7 2022	Wadi Al Ramahi et al., The International Arabic Journal of Antimicrobial Agents, doi:10.3823/862	The Effect of Vitamin D treatment on COVID 19- Patients, an Inverted Propensity Score Weighting (IPSW), and Inverted Probability of Treatment Weighting (IPTW) Analyzed Study
	Retrospective study comparing 847 patients receiving ≤149,000IU vitamin D and 170 receiving ≥150,000IU, showing no significant differences, however the result may not be very meaningful - membership in the higher cumulative dose group req..
Mar 2 2022	Karonova et al., Pharmaceuticals, doi:10.3390/ph15030305	Vitamin D Status and Immune Response in Hospitalized Patients with Moderate and Severe COVID-19
	22% lower severe cases (p=0.01). Retrospective 331 hospitalized patients in Russia, showing lower risk of severe cases with higher vitamin D levels.
Mar 1 2022	Hemdan, D., Materials Express, doi:10.1166/mex.2022.2168	Level of vitamins and minerals for people with coronavirus (Covid-19) in Taif, Kingdom of Saudi Arabia
	31% lower mortality (p=0.02). Retrospective 193 COVID-19 patients in Saudi Arabia, showing higher vitamin B12 levels associated with mortality, and higher mortality with vitamin D deficiency.
Feb 28 2022	Shehab et al., Tropical Journal of Pharmaceutical Research, doi:10.4314/tjpr.v21i2.13	Immune-boosting effect of natural remedies and supplements on progress of, and recovery from COVID-19 infection
	46% lower severe cases (p=0.2). Retrospective survey-based analysis of 349 COVID-19 patients, showing a lower risk of severe cases with vitamin D, zinc, turmeric, and honey prophylaxis in unadjusted analysis, without statistical significance. REC/UG/2020/03.
Feb 28 2022	Nimer et al., Bosnian Journal of Basic Medical Sciences, doi:10.17305/bjbms.2021.7009	The impact of vitamin and mineral supplements usage prior to COVID-19 infection on disease severity and hospitalization
	33% lower hospitalization (p=0.001) and 29% lower severe cases (p=0.01). Retrospective 2,148 COVID-19 recovered patients in Jordan, showing lower risk of severity and hospitalization with vitamin D prophylaxis.
Feb 24 2022	Rodríguez-Vidales et al., Nutrición Hospitalaria, doi:10.20960/nh.03731	Severe COVID-19 patients have severe vitamin D deficiency in Northeast Mexico
	39% lower severe cases (p=0.05). Retrospective 181 diagnostic center patients and 116 ICU patients in Mexico, showing higher risk of severity with vitamin D levels <10ng/mL.
Feb 24 2022	Kory et al., Journal of Clinical Medicine Research, doi:10.14740/jocmr4658	“MATH+” Multi-Modal Hospital Treatment Protocol for COVID-19 Infection: Clinical and Scientific Rationale
	Review of the data supporting the MATH+ hospital treatment protocol for COVID-19.
Feb 22 2022	Tylicki et al., Viruses, doi:10.3390/v14030451	Angiotensin Converting Enzyme Inhibitors May Increase While Active Vitamin D May Decrease the Risk of Severe Pneumonia in SARS-CoV-2 Infected Patients with Chronic Kidney Disease on Maintenance Hemodialysis
	45% lower severe cases (p=0.02). Retrospective 85 COVID+ hemodialysis patients in Poland, showing lower severity with existing vitamin D use. Patients in this study are also analyzed in [Tylicki].
Feb 21 2022	Saeed et al., The Egyptian Journal of Internal Medicine, doi:10.1186/s43162-022-00116-w	Cholecalciferol level and its impact on COVID-19 patients
	Prospective study of 414 COVID+ ICU patients in Egypt, showing mortality associated with lower vitamin D levels.
Feb 19 2022	Zidrou et al., Cureus, doi:10.7759/cureus.22385	The Relationship Between Vitamin D Status and the Clinical Severity of COVID-19 Infection: A Retrospective Single-Center Analysis
	18% lower progression (p=0.26) and 38% shorter hospitalization (p=0.16). Retrospective 71 hospitalized COVID-19 patients in Greece with vitamin D levels measured within 48 hours of admission, showing longer hospitalization, more radiographic findings, and higher inflammatory and cellular damage markers with vi..
Feb 19 2022	Sanson et al., Irish Journal of Medical Science (1971 -), doi:10.1007/s11845-022-02952-9	A combined role for low vitamin D and low albumin circulating levels as strong predictors of worse outcome in COVID-19 patients
	64% lower progression (p=0.03). Prospective study of 69 hospitalized COVID-19 pneumonia patients, showing higher risk of combined NIV/IMV/60-day death with low vitamin D levels.
Feb 18 2022	Cannata-Andía et al., BMC Medicine, doi:10.1186/s12916-022-02290-8	A single-oral bolus of 100,000 IU of cholecalciferol at hospital admission did not improve outcomes in the COVID-19 disease: the COVID-VIT-D — a randomised multicentre international clinical trial
	44% higher mortality (p=0.31), 5% higher ICU admission (p=0.82), and 5% longer hospitalization. RCT 274 very late stage (>80% pulmonary involvement at baseline) hospitalized COVID-19 patients treated with a single dose of cholecalciferol, and 269 control patients, showing no significant differences. High serum calcidiol levels at ad..
Feb 17 2022	Junior et al., BMC Geriatrics, doi:10.1186/s12877-022-02776-3	Chronic diseases, chest computed tomography, and laboratory tests as predictors of severe respiratory failure and death in elderly Brazilian patients hospitalized with COVID-19: a prospective cohort study
	22% lower mortality (p=0.61) and 31% lower progression (p=0.26). Prospective study of 201 COVID+ hospitalized adults in Brazil, mean age 73, showing a lower risk of mortality and respiratory failure with vitamin D supplementation in unadjusted results, without statistical significance, and a higher ris..
Feb 15 2022	Shah et al., QJM: An International Journal of Medicine, doi:10.1093/qjmed/hcac040	Does vitamin D supplementation reduce COVID-19 severity? - a systematic review
	52% lower mortality (p<0.0001), 46% lower ventilation (p<0.0001), and 64% lower ICU admission (p<0.0001). Meta-analysis of seven systematic reviews showing that vitamin D supplementation reduces the risk of COVID-19 mortality, ventilation, and ICU admission. Authors note that oral and IV supplements were well tolerated, safe, and effective.
Feb 8 2022	Bushnaq et al., International Journal of Environmental Research and Public Health, doi:10.3390/ijerph19031901	The Impact of Vitamin D Status on COVID-19 Severity among Hospitalized Patients in the Western Region of Saudi Arabia: A Retrospective Cross-Sectional Study
	32% lower ventilation (p=0.27) and 4% lower ICU admission (p=0.87). Retrospective 197 hospitalized patients in Saudi Arabia, showing no significant differences based on vitamin D levels. Adjusted results are provided only for vitamin D as a continuous variable.
Feb 5 2022	Bishop et al., Nutrition, doi:10.1016/j.nut.2022.111899 (date from preprint)	REsCue Trial: Randomized Controlled Clinical Trial with Extended-Release Calcifediol in Symptomatic COVID-19 Outpatients
	85% lower progression (p=0.25) and 34% improved recovery (p=0.56). Small RCT with low-risk patients in the USA showing no significant differences in overall recovery. Minimal details on outcomes are provided in the preprint. Authors note significantly faster resolution of respiratory symptoms when treatm..
Feb 2 2022	Grant et al., Nutrients, doi:10.3390/nu14030639	A Narrative Review of the Evidence for Variations in Serum 25-Hydroxyvitamin D Concentration Thresholds for Optimal Health
	Review of the benefits of vitamin D for cardiovascular disease, hypertension, cancer, type 2 diabetes, and COVID-19. Authors conclude that optimal levels are above 30ng/mL for cardiovascular disease and all-cause mortality, whereas the th..
Jan 31 2022	AlKhafaji et al., International Journal of General Medicine, doi:10.2147/ijgm.s346169	The Impact of Vitamin D Level on the Severity and Outcome of Hospitalized Patients with COVID-19 Disease
	39% lower mortality (p=0.5), 31% lower ventilation (p=0.51), and 42% lower ICU admission (p=0.2). Retrospective 203 hospitalized COVID-19 patients in Saudi Arabia, showing no significant difference in outcomes with vitamin D deficiency.
Jan 31 2022	Levy et al., Gerontology, doi:10.1159/000521412	Frail Older Adults with Presymptomatic SARS-CoV-2 Infection: Clinical Course and Prognosis
	30% lower combined mortality/hospitalization (p=0.05). Retrospective 849 COVID-19+ patients in skilled nursing homes, showing lower risk of combined hospitalization/death with vitamin D prophylaxis, very close to statistical significance.
Jan 31 2022	Subramanian et al., The American Journal of Clinical Nutrition, doi:10.1093/ajcn/nqac027	Vitamin D, D-binding protein, free vitamin D and COVID-19 mortality in hospitalized patients
	27% lower mortality (p=0.12). Retrospective 427 hospitalized COVID-19 patients in the United Kingdom, showing lower mortality with vitamin D supplementation (p=0.12), and higher mortality with both low and high vitamin D levels compared to a reference range of 50-74 n..
Jan 29 2022	Mohajeri et al., Mediterranean Journal of Nutrition and Metabolism, doi:10.3233/MNM-211521	The difference in the dietary inflammatory index, functional food, and antioxidants intake between COVID-19 patients and healthy persons
	Retrospective dietary survey analysis of 500 COVID-19 patients and 500 healthy matched controls in Iran, showing that COVID-19 patients had lower daily consumption of vitamin C, vitamin D, vitamin E, zinc, and selenium. IR.ARUMS.REC.1400...
Jan 27 2022	Schmitt et al., Journal of Medical Virology, doi:10.1002/jmv.27606	Oxidative stress status and vitamin D levels of asymptomatic to mild symptomatic COVID-19 infections during the third trimester of pregnancy: A retrospective study in Metz, France
	Retrospective 15 COVID+ pregnant women and 20 healthy controls in France, showing that all COVID+ patients were vitamin D deficient, and vitamin D levels were significantly lower in symptomatic patients compared to controls or asymptomati..
Jan 24 2022	Karonova et al., Nutrients, doi:10.3390/nu14030505	Vitamin D Intake May Reduce SARS-CoV-2 Infection Morbidity in Health Care Workers
	95% fewer symptomatic cases (p=0.002) and 42% fewer cases (p=0.1). Small RCT with 45 high dose vitamin D patients (50,000IU/wk for 2 wks followed by 5,000IU/day) and 46 low dose patients (2,000IU/day), showing lower cases and lower symptomatic cases with high dose treatment.
Jan 24 2022	Saponaro et al., Frontiers in Immunology, doi:10.3389/fimmu.2021.745713	Is There a Crucial Link Between Vitamin D Status and Inflammatory Response in Patients With COVID-19?
	36% lower ARDS (p=0.43). Retrospective 93 COVID-19 pneumonia patients in Italy, showing low vitamin D levels associated with severe ARDS, and significantly lower vitamin D levels for non-survivors.
Jan 22 2022	Smaha et al., International Journal of Infectious Diseases, doi:10.1016/j.ijid.2022.01.044	COVID-19 pneumonia patients with 25(OH)D levels lower than 12 ng/ml are at increased risk of death
	19% lower mortality (p=0.05). Retrospective 357 COVID-19 pneumonia patients in Slovakia, showing higher mortality with vitamin D deficiency (<12ng/mL). All patients received vitamin D supplementation in hospital. In multivariable linear regression, vitamin D levels we..
Jan 21 2022	Tyrovolas et al., Nutrients, doi:10.3390/nu14030471	COVID-19 Mortality in Europe, by Latitude and Obesity Status: A Geo-Spatial Analysis in 40 Countries
	Ecological study of 40 European countries showing higher COVID-19 incidence and mortality associated with higher latitude (as a proxy for lower sunlight exposure and vitamin D synthesis). The association was stronger for countries with..
Jan 15 2022	Tentolouris et al., Diabetes/Metabolism Research and Reviews, doi:10.1002/dmrr.3517	The effect of vitamin D supplementation on mortality and intensive care unit admission of COVID-19 patients. A systematic review, meta-analysis and meta-regression
	40% lower mortality (p=0.11) and 67% lower ICU admission (p=0.005). Systematic review and meta analysis of 10 vitamin D studies showing lower mortality, and ICU admission with treatment, statistically significant only for ICU admission.
Jan 15 2022	Soltani-Zangbar et al., Gene Reports, doi:10.1016/j.genrep.2022.101509	Serum levels of vitamin D and immune system function in patients with COVID-19 admitted to intensive care unit
	Analysis of 50 COVID-19 ICU patients and 50 healthy controls in Iran, showing significantly lower vitamin D levels in COVID-19 patients.
Jan 13 2022	Mansouri et al., Scientific Reports, doi:10.1038/s41598-022-04778-y	The impact of calcitriol and estradiol on the SARS-CoV-2 biological activity: a molecular modeling approach
	In silico study predicting that calcitriol and estradiol disrupt the interaction between the SARS-CoV-2 spike protein and ACE2. Authors note that calcitriol may be more effective in the presence of estradiol.
Jan 13 2022	Regalia et al., Nutrients, doi:10.3390/nu14020317	Vitamin D Status and SARS-CoV-2 Infection in a Cohort of Kidney Transplanted Patients
	33% fewer cases (p=0.21). Retrospective 61 COVID+ kidney transplant patients and 122 matched controls, showing significantly lower vitamin D levels in COVID+ patients, and lower cases with vitamin D supplementation, without statistical significance.
Jan 7 2022	Al-Saleh et al., BioMetals, doi:10.1007/s10534-021-00355-48	Essential metals, vitamins and antioxidant enzyme activities in COVID-19 patients and their potential associations with the disease severity
	Prospective study of 155 COVID-19 patients in Saudi Arabia, showing that 68% of patients were vitamin D deficient (<20.05 μg/L). Vitamin D levels were not significantly different between the asymptomatic (mean 10.9 μg/L), mild (14.2 μg/L)..
Jan 6 2022	Tylicki et al., Journal of Clinical Medicine, doi:10.3390/jcm11020285	Predictors of Mortality in Hemodialyzed Patients after SARS-CoV-2 Infection
	14% lower mortality (p=0.61). Retrospective 133 COVID+ hemodialysis patients in Poland, showing lower mortality with existing vitamin D use, without statistical significance.
Jan 1 2022	Seal et al., Journal of General Internal Medicine, doi:10.1007/s11606-021-07170-0	Association of Vitamin D Status and COVID-19-Related Hospitalization and Mortality
	45% lower mortality (p=0.001) and 22% lower hospitalization (p=0.01). Retrospective 4,599 COVID+ veterans in the USA with vitamin D levels measured 15 to 90 days prior to testing positive, showing a significant independent inverse dose-response relationship between vitamin D levels (from 15 to 60ng/mL) and ..
Jan 1 2022	Bilir et al., Journal of Contemporary Medicine, doi:10.16899/jcm.990057	Does Vitamin D Supplementation Reduce Cytokine Storm and Mortality in Geriatric Intensive Care Patients Diagnosed with COVID-19
	23% lower mortality (p=0.26), 3% lower ventilation (p=1), 20% improved recovery (p=0.13), and 10% shorter ICU admission (p=0.44). Retrospective 80 elderly ICU patients in Turkey, 40 with vitamin D levels <30ng/ml received vitamin D treatment, showing no significant differences in outcomes. Although not statistically significant, results favored treatment which sugge..
Dec 31 2021	Jabbar et al., Natural Volatiles & Essential Oils, 8:4	Vitamin D Serum Levels and Its Association With COVID 19 Infection In Babylon Governorate, Iraq
	Analysis of 120 COVID-19 and 120 control patients in Iraq, showing significantly lower vitamin D levels for COVID-19 patients.
Dec 31 2021	Efird et al., International Journal of Environmental Research and Public Health, doi:10.3390/ijerph19010447	The Interaction of Vitamin D and Corticosteroids: A Mortality Analysis of 26,508 Veterans Who Tested Positive for SARS-CoV-2
	49% lower mortality (p=0.1). Retrospective 26,508 COVID+ veterans in USA, showing lower mortality with vitamin D use after testing positive (defined as being administered ≥7 days or half of the survival time within 2 weeks after testing), with statistical significanc..
Dec 31 2021	Murai et al., Clinics, doi:10.6061/clinics/2021/e3549	Effect of a Single High-Dose Vitamin D3 on the Length of Hospital Stay of Severely 25-Hydroxyvitamin D-Deficient Patients with COVID-19
	37% shorter hospitalization (p=0.27) and 12% higher hospital discharge (p=0.76). Analysis of a subset of patients from [Murai] with vitamin D < 10 ng/mL, showing improved results with vitamin D treatment, without statistical significance in the small sample.
Dec 29 2021	Mahmood et al., European Journal of Medical and Health Sciences, doi:10.24018/ejmed.2021.3.6.1159	Coronavirus in HIP Fractures CHIP 2: Is Vitamin D Deficiency Associated with Increased Mortality from COVID-19 Infections in A Hip Fracture Population?
	9% lower mortality (p=0.67). Retrospective 517 hip fracture patients in the UK with vitamin D levels measured during COVID-19 admission, not showing significant differences in mortality for supplementation in unadjusted analysis with no group details and subject to c..
Dec 28 2021	Baguma et al., Research Square, doi:10.21203/rs.3.rs-1193578/v1	Characteristics of the COVID-19 patients treated at Gulu Regional Referral Hospital, Northern Uganda: A cross-sectional study
	97% lower mortality (p=0.02). Retrospective COVID+ hospitalized patients in Uganda, 23 patients receiving vitamin D treatment, showing significantly lower mortality with treatment.
Dec 25 2021	Apaydin et al., Clinical Endocrinology, doi:10.1111/cen.14664	Effects of vitamin D receptor gene polymorphisms on the prognosis of COVID‐19
	Analysis of 297 hospitalized COVID-19 patients in Turkey, showing no significant association between vitamin D levels and severity, ICU admission, or mortality. VDR gene polymorphisms were independently associated with COVID-19 severity a..
Dec 22 2021	Chiodini et al., Frontiers in Public Health, doi:10.3389/fpubh.2021.736665	Vitamin D Status and SARS-CoV-2 Infection and COVID-19 Clinical Outcomes
	Meta analysis concluding that "patients with low vitamin D levels present an increased risk of ARDS requiring admission to intensive care unit (ICU) or mortality due to SARS-CoV-2 infection and a higher susceptibility to SARS-CoV-2 i..
Dec 10 2021	Putra et al., European Journal of Medical and Health Sciences, doi:10.24018/ejmed.2021.3.6.1131	Vitamin D Levels among Hospitalized and Non-Hospitalized COVID-19 Patients in Dr. M. Djamil General Hospital Padang
	26% lower hospitalization (p=0.59). Case control study in Indonesia with 31 moderate to critical hospitalized COVID-19 patients, and 31 asymptomatic or mild non-hospitalized COVID-19 patients, showing lower vitamin D levels in the hospitalized patients, without reaching sta..
Dec 3 2021	Ma et al., The American Journal of Clinical Nutrition, doi:10.1093/ajcn/nqab389	Associations between predicted vitamin D status, vitamin D intake, and risk of SARS-CoV-2 infection and Coronavirus Disease 2019 severity
	49% lower hospitalization (p=0.04), 7% more symptomatic cases (p=0.25), and 17% fewer cases (p=0.07). Analysis of 39,915 patients with 1,768 COVID+ cases based on surveys in the Nurses' Health Study II, showing higher predicted vitamin D levels associated with lower risk of COVID-19 cases. There was significantly lower risk of hospitaliza..
Nov 30 2021	Fatemi et al., Acute and Critical Care, doi:10.4266/acc.2021.00605	Association of vitamin D deficiency with COVID-19 severity and mortality in Iranian people: a prospective observational study
	42% lower mortality (p=0.07) and 38% lower severe cases (p=0.007). Prospective study of 248 hospitalized COVID+ patients in Iran with vitamin D levels measured in the previous year and again at admission, showing vitamin D status associated with severity and mortality.
Nov 30 2021	Kaur et al., Indian Journal of Clinical Practice, 32:6	Correlation of Vitamin D Levels with COVID-19 Severity and Outcome
	90% lower mortality (p<0.0001) and 90% lower ventilation (p<0.0001). Prospective study of 81 hospitalized COVID+ patients in India, showing low vitamin D levels associated with COVID-19 severity and mortality.
Nov 29 2021	Ranjbar et al., Journal of Research in Medical Sciences, doi:10.4103/jrms.JRMS_1151_20	Serum level of Vitamin D is associated with COVID-19 mortality rate in hospitalized patients
	42% lower mortality (p=0.07). Retrospective 317 COVID-19 hospitalized patients in Iran, showing mortality associated with lower vitamin D levels.
Nov 24 2021	Jenei et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2021.11.025	COVID-19 mortality is associated with low Vitamin D levels in patients with risk factors and/or advanced age
	Retrospective 257 hospitalized patients in Hungary, showing mortality associated with lower vitamin D levels for all patients, for patients >60, and for age-matched patients with risk factors or age >60. The non-age-matched analyses are c..
Nov 23 2021	Ahmed et al., BioMed Research International, doi:10.1155/2021/1676914	Factors Affecting the Incidence, Progression, and Severity of COVID-19 in Type 1 Diabetes Mellitus
	Retrospective type 1 diabetes patients in Saudi Arabia showing that mean vitamin D levels were significantly lower in type 1 diabetes patients with COVID-19 than in type 1 diabetes patients without COVID-19, or in a control group of patie..
Nov 23 2021	Seven et al., The Journal of Maternal-Fetal & Neonatal Medicine, doi:10.1080/14767058.2021.2005564	Correlation between 25-hydroxy vitamin D levels and COVID-19 severity in pregnant women: a cross-sectional study
	47% lower severe cases (p=0.006). Prospective study of 403 pregnant COVID+ hospitalized women in Turkey, showing higher risk of severe disease or poor prognostic factors with vitamin D deficiency.
Nov 21 2021	Ahmed et al., medRxiv, doi:10.1101/2021.11.18.21266489	Causal Inference and COVID-19 Nursing Home Patients: Identifying Factors That Reduced Mortality Risk
	10% lower mortality (p=0.28). Retrospective causal inference analysis of 4,091 COVID+ long-term care high risk patients in the USA, showing lower mortality with vitamin D, without statistical significance.
Nov 21 2021	Asgari et al., Acta Medica Iranica, doi:10.18502/acta.v59i11.7779	Vitamin D Insufficiency in Disease Severity and Prognosis of the Patients With SARS Corona Virus-2 Infection
	73% lower mortality (p=0.03) and 66% lower progression (p=0.02). Retrospective 98 moderate/severe hospitalized COVID-19+ patients in Iran, showing significantly increased risk of mortality and severity with vitamin D deficiency. IR.AJAUMS.REC.1399.060.
Nov 15 2021	Ramos et al., Global Journal of Health Science, doi:10.5539/gjhs.v14n1p1	Vitamin D, Zinc and Iron in Adult Patients with Covid-19 and Their Action in the Immune Response as Biomarkers
	46% fewer cases (p=0.16). Retrospective 13 COVID-19 patients and 7 controls in Brazil, showing higher prevalence of vitamin D deficiency for COVID-19 cases, without statistical significance.
Nov 14 2021	Beigmohammadi et al., Trials, doi:10.1186/s13063-021-05795-4	The effect of supplementation with vitamins A, B, C, D, and E on disease severity and inflammatory responses in patients with COVID-19: a randomized clinical trial
	89% lower mortality (p=0.11), 41% lower hospitalization (p=0.25), and 45% improved recovery (p=0.001). Small RCT 60 ICU patients in Iran, 30 treated with vitamins A, B, C, D, and E, showing significant improvement in SOFA score and several inflammatory markers at day 7 with treatment. 5,000 IU vitamin A daily, 600,000 IU vitamin D once, 30..
Nov 12 2021	Sacristán et al., Transplantation Proceedings, doi:10.1016/j.transproceed.2021.08.060	Risk of severe COVID-19 infection in kidney transplant recipients
	Retrospective 63 COVID+ kidney transplant recipients, showing significantly lower vitamin D levels before infection in patients requiring ICU admission.
Nov 12 2021	Gönen et al., Nutrients, doi:10.3390/nu13114047	Rapid and Effective Vitamin D Supplementation May Present Better Clinical Outcomes in COVID-19 (SARS-CoV-2) Patients by Altering Serum INOS1, IL1B, IFNg, Cathelicidin-LL37, and ICAM1
	21% lower hospitalization (p=0.11). Retrospective 867 hospitalized COVID-19 patients in Turkey, showing worse outcomes with vitamin D deficiency (without statistical significance); followed by a prospective study of 210 patients with vitamin D supplementation for those that..
Nov 10 2021	Asghar et al., Am. J. Trop. Med. Hyg., doi:10.4269/ajtmh.21-0577	Evaluation of Vitamin-D Status and Its Association with Clinical Outcomes Among COVID-19 Patients in Pakistan
	53% lower mortality (p=0.05), 19% lower ventilation (p=0.32), and 33% lower ICU admission (p=0.54). Retrospective 91 hospitalized patients in Pakistan, showing vitamin D deficiency associated with mortality in multivariate Cox regression.
Nov 3 2021	Gallelli et al., Nutrients, doi:10.3390/nu13113932	Vitamin D Serum Levels in Subjects Tested for SARS-CoV-2: What Are the Differences among Acute, Healed, and Negative COVID-19 Patients? A Multicenter Real-Practice Study
	Analysis of 117 patients in Italy, showing COVID-19 patients had significantly lower vitamin D levels than control patients.
Nov 2 2021	Atanasovska et al., Redox Report, doi:10.1080/13510002.2021.1999126	Vitamin D levels and oxidative stress markers in patients hospitalized with COVID-19
	59% lower severe cases (p=0.13). Retrospective 33 COVID-19 hospitalized patients in North Macedonia, showing significantly lower vitamin D levels for severe vs. moderate cases. Oxidative stress was also higher for vitamin D insufficient patients.
Oct 25 2021	Leal-Martínez et al., International Journal of Environmental Research and Public Health, doi:10.3390/ijerph19031172 (date from preprint)	Effect of a Nutritional Support System to Increase Survival and Reduce Mortality in Patients with COVID-19 in Stage III and Comorbidities: A Blinded Randomized Controlled Clinical Trial
	86% lower mortality (p=0.03) and 57% lower ventilation (p=0.31). 80 patient RCT with 40 patients treated with a comprehensive regimen of nutritional support, showing significantly lower mortality with treatment. Treatment contained cholecalciferol, vitamin C, zinc, spirulina maxima, folic acid, glutami..
Oct 22 2021	Hurst et al., BMJ Open, doi:10.1136/bmjopen-2021-055435	Vitamin D insufficiency in COVID-19 and influenza A, and critical illness survivors: a cross-sectional study
	68% lower mortality (p=0.005) and 66% lower ventilation (p=0.004). Analysis of 259 hospitalized COVID-19 patients in the UK, showing a majority of patients had vitamin D deficiency/insufficiency, which was associated with poor outcomes. Both free and total 25(OH)D were analyzed with consistent results...
Oct 20 2021	Al-Anouti et al., Nutrients, doi:10.3390/nu13113680	Associations between Genetic Variants in the Vitamin D Metabolism Pathway and Severity of COVID-19 among UAE Residents
	68% lower severe cases (p=0.0007). Retrospective 646 COVID-19 patients in the UAE, showing significant associations between genetic determinants of vitamin D metabolism and COVID-19 severity, and an association with vitamin D deficiency and COVID-19 severity. Patients in t..
Oct 15 2021	Ramirez-Sandoval et al., Archives of Medical Research, doi:10.1016/j.arcmed.2021.09.006	Very Low Vitamin D Levels are a Strong Independent Predictor of Mortality in Hospitalized Patients with Severe COVID-19
	32% lower mortality (p<0.0001) and 22% shorter hospitalization (p=0.001). Retrospective 2,908 hospitalized patients in Mexico with vitamin D levels measured on admission, showing significantly lower mortality for patients without vitamin D deficiency.
Oct 13 2021	Maghbooli et al., Endocrine Practice, doi:10.1016/j.eprac.2021.09.016	Treatment with 25-hydroxyvitamin D3 (calcifediol) is associated with a reduction in the blood neutrophil-to-lymphocyte ratio marker of disease severity in patients hospitalized with COVID-19: a pilot, multicenter, randomized, placebo-controlled double blind clinical trial
	40% lower ICU admission (p=0.42) and 17% shorter hospitalization (p=0.1). RCT 106 hospitalized patients with vitamin D levels <30ng/ml in Iran, 53 treated with calcifediol, showing that treatment was able to correct vitamin D deficiency/insufficiency, resulting in improved immune system function. Hospitalizatio..
Oct 12 2021	Afaghi et al., The Tohoku Journal of Experimental Medicine, doi:10.1620/tjem.255.127	Prevalence and Clinical Outcomes of Vitamin D Deficiency in COVID-19 Hospitalized Patients: A Retrospective Single-Center Analysis
	55% lower mortality (p=0.002), 56% lower ventilation (p<0.0001), and 34% lower ICU admission (p=0.0001). Retrospective 646 COVID-19+ hospitalized patients in Iran, showing higher mortality with vitamin D deficiency.
Oct 12 2021	Worcel et al., Annals of Palliative Medicine, doi:10.21037/apm-21-1707	Low mortality from COVID-19 at a nursing facility in France following a combined preventive and active treatment protocol
	Report on the relatively low mortality and relatively mild COVID-19 symptoms at a French nursing facility that has adopted several treatments including vitamin D, zinc, anticoagulants, corticosteroids, and a multivitamin.
Oct 9 2021	Caballero-García et al., Medicina, doi:10.3390/medicina57101079	Effect of Vitamin D Supplementation on Muscle Status in Old Patients Recovering from COVID-19 Infection
	Small RCT with 30 patients examining the effect of vitamin D supplementation on muscle status in elderly recovering COVID-19 patients, showing serum creatine kinase levels returned to optimal values, however there was no significant diffe..
Oct 8 2021	Szarpak et al., Cardiology Journal, doi:10.5603/CJ.a2021.0122	Vitamin D supplementation to treat SARS-CoV-2 positive patients. Evidence from meta-analysis
	44% lower mortality (p=0.2), 62% lower ventilation (p=0.02), and 81% lower ICU admission (p=0.003). Meta analysis of 8 studies with 2,322 patients showing that vitamin D treatment was associated with significantly lower ICU admission and need for mechanical ventilation.
Oct 5 2021	Mukherjee et al., FEBS Open Bio, doi:10.1002/2211-5463.13309	Seasonal UV exposure and vitamin D: Association with the dynamics of COVID-19 transmission in Europe
	Analysis of UV and temperature levels in 26 European countries, showing that low temperature, UV index, and cloud-free vitamin D UV dose levels were negatively correlated with COVID-19 prevalence. Authors suggest that low UV exposure can ..
Oct 2 2021	Abdollahzadeh et al., Infection, Genetics and Evolution, doi:10.1016/j.meegid.2021.105098	Association of Vitamin D receptor gene polymorphisms and clinical/severe outcomes of COVID-19 patients
	Analysis of 500 hospitalized patients in Iran, showing associations between specific vitamin D receptor gene polymorphisms and COVID-19 outcomes.
Sep 27 2021	Yildiz et al., Bratislava Medical Journal, doi:10.4149/BLL_2021_119	The prognostic significance of vitamin D deficiency in patients with COVID-19 pneumonia
	81% lower mortality (p=0.04), 94% lower ICU admission (p=0.13), and 10% shorter hospitalization (p=0.32). Retrospective 207 hospitalized patients in Turkey, 37 with vitamin D levels <30ng/ml treated with a single dose of 300,000IU vitamin D, showing lower mortality with treatment.
Sep 25 2021	Borsche et al., Nutrients, doi:10.3390/nu13103596 (date from preprint)	COVID-19 Mortality Risk Correlates Inversely with Vitamin D3 Status, and a Mortality Rate Close to Zero Could Theoretically Be Achieved at 50 ng/mL 25(OH)D3: Results of a Systematic Review and Meta-Analysis
	Meta analysis of 8 studies with vitamin D levels measured pre-infection or on the day of hospital admission, showing a correlation between the levels and mortality. Authors recommend combining vaccination with vitamin D supplementation to..
Sep 24 2021	Arroyo-Díaz et al., Frontiers in Public Health, doi:10.3389/fpubh.2021.758347	Previous Vitamin D Supplementation and Morbidity and Mortality Outcomes in People Hospitalised for COVID19: A Cross-Sectional Study
	12% higher mortality (p=0.59), 43% lower ventilation (p=0.22), 44% lower ICU admission (p=0.03), and 12% shorter hospitalization (p=0.2). Retrospective 1,267 hospitalized patients in Spain, 189 on vitamin D supplementation before admission, showing lower ICU admission with supplementation, and no statistically significant difference for mortality or ventilation.
Sep 22 2021	Castle et al., Journal of Inflammation Research, doi:10.2147/JIR.S323356	Implications for Systemic Approaches to COVID-19: Effect Sizes of Remdesivir, Tocilizumab, Melatonin, Vitamin D3, and Meditation
	Review of the effects of COVID-19 on inflammatory markers, and the effects on those markers of standard treatments vs. vitamin D, melatonin, and meditation, showing comparable or superior effects with the non-standard treatments. The stan..
Sep 22 2021	Marino-Ramirez et al., medRxiv, doi:10.1101/2021.09.20.21263865	Vitamin D and socioeconomic deprivation mediate COVID-19 ethnic health disparities
	UK Biobank retrospective showing that vitamin supplements, including vitamin D, mediate the Asian disparity in COVID-19 susceptibility, and vitamin D levels mediate Asian and Black COVID-19 severity disparities. Authors conclude that the ..
Sep 20 2021	Israel et al., Internal and Emergency Medicine, doi:10.1007/s11739-021-02902-w	Vitamin D deficiency is associated with higher risks for SARS-CoV-2 infection and COVID-19 severity: a retrospective case–control study
	34% lower severe cases (p=0.0001) and 20% fewer cases (p<0.0001). Retrospective 41,757 PCR+ patients in Israel and 417,570 matched controls, showing an inverse correlation between vitamin D levels and the risks of SARS-CoV-2 infection and of severe disease in those infected. COM-0046-20.
Sep 19 2021	Derakhshanian et al., Food Science & Nutrition, doi:10.1002/fsn3.2591	The predictive power of serum vitamin D for poor outcomes in COVID-19 patients
	45% lower mortality (p=0.05), 42% lower ventilation (p=0.09), and 37% lower ICU admission (p=0.04). Retrospective 290 hospitalized patients in Iran, showing higher mortality with vitamin D deficiency.
Sep 14 2021	Padhi et al., International Immunopharmacology, doi:10.1016/j.intimp.2020.107001	Lower levels of vitamin D are associated with SARS-CoV-2 infection and mortality in the Indian population: An observational study
	Analysis of vitamin D levels and COVID-19 in Indian states and union territories, showing an inverse correlation of vitamin D levels with SARS-CoV-2 cases and mortality.
Sep 9 2021	Pickard et al., PLOS Pathogens, doi:10.1371/journal.ppat.1009840	Discovery of re-purposed drugs that slow SARS-CoV-2 replication in human cells
	In vitro studying identifying 35 compounds that inhibit SARS-CoV-2 in Vero cells and hepatocytes when treated prior to infection, and several compounds that slow replication when treated after infection: vitamin D, amodiaquine, atovaquone..
Sep 8 2021	Elamir et al., Bone, doi:10.1016/j.bone.2021.116175	A Randomized Pilot Study Using Calcitriol in Hospitalized Patients
	86% lower mortality (p=0.23), 38% lower ICU admission (p=0.33), 40% shorter hospitalization (p=0.14), and 86% improved recovery (p=0.03). RCT 50 hospitalized patients in the USA, 25 treated with calcitriol, showing significantly improved oxygenation with treatment. Mortality, intubation, ICU admission, and hospitalization time also favored treatment, while not reaching stat..
Sep 6 2021	Zafar et al., Postgraduate Medical Journal, doi:10.1136/postgradmedj-2021-140564	Vitamin D levels and mortality with SARS-COV-2 infection: a retrospective two-centre cohort study
	43% higher mortality (p=0.71). Retrospective 433 patients in the UK, 52 positive for COVID-19, showing no significant difference in mortality based on vitamin D levels. Authors also include results for all 433 patients, however given the expected test false negative ra..
Sep 5 2021	Lázaro et al., Endocrine Abstracts, doi:10.1530/endoabs.70.EP552	Vitamin D deficit in type 2 diabetes patients during COVID-19 lockdown with and without supplementation
	27% fewer cases (p=1). Analysis of 239 consecutive diabetic patients, 97 taking vitamin D supplements, showing significantly higher vitamin D levels in supplemented patients. There was no statistically significant difference in cases based on supplementation, w..
Sep 1 2021	Bagheri et al., Journal of Family & Reproductive Health, doi:10.18502/jfrh.v14i3.4668	Supplement Usage Pattern in a Group of COVID-19 Patients in Tehran
	71% lower severe cases (p=0.02) and 38% lower hospitalization (p=0.11). Retrospective 510 patients in Iran, showing lower risk of severity with vitamin D (statistically significant) and zinc (not statistically significant) supplementation. IR.TUMS.VCR.REC.1398.1063.
Sep 1 2021	Soliman et al., Proceedings of Singapore Healthcare, doi:10.1177/20101058211041405	Impact of Vitamin D Therapy on the Progress COVID-19: Six Weeks Follow-Up Study of Vitamin D Deficient Elderly Diabetes Patients
	63% lower mortality (p=0.21), 20% lower ventilation (p=0.56), and 20% improved recovery (p=0.56). Small RCT with 56 eldery diabetes patients hospitalized in Egypt, 40 treated with cholecalciferol, not showing significant differences.
Aug 31 2021	Ben-Eltriki et al., Journal of the American College of Nutrition, doi:10.1080/07315724.2021.1951891	Association between Vitamin D Status and Risk of Developing Severe COVID-19 Infection: A Meta-Analysis of Observational Studies
	Meta analysis of 24 observational studies with 3,637 participants, showing low vitamin D status associated with a higher risk of death and a higher risk of developing severe COVID-19 pneumonia.
Aug 29 2021	Karonova et al., Nutrients, doi:10.3390/nu13093021	Low 25(OH)D Level Is Associated with Severe Course and Poor Prognosis in COVID-19
	78% lower mortality (p=0.006) and 67% lower severe cases (p=0.005). Retrospective 161 hospitalized patients in Russia, showing COVID-19 severity and mortality associated with vitamin D deficiency. Patients in this study may overlap with those in an earlier smaller study from some of the same authors.
Aug 28 2021	Assiri et al., Journal of Infection and Public Health, doi:10.1016/j.jiph.2021.08.030	COVID-19 related treatment and outcomes among COVID-19 ICU patients: A retrospective cohort study
	66% higher mortality (p=0.6). Retrospective 118 ICU patients in Saudi Arabia showing no significant differences in unadjusted results with zinc, vitamin D, and favipiravir treatment. This paper has several data issues: The text states the outcome variable was coded as..
Aug 27 2021	Pecina et al., Journal of Primary Care & Community Health, doi:10.1177/21501327211041206	Vitamin D Status and Severe COVID-19 Disease Outcomes in Hospitalized Patients
	70% higher mortality (p=0.52), 10% higher ventilation (p=0.89), and 30% higher ICU admission (p=0.61). Retrospective 92 hospitalized patients not showing significant differences in outcomes based on vitamin D status or supplementation.
Aug 26 2021	Golabi et al., Nutrients, doi:10.3390/nu13103368 (date from preprint)	The Association between Vitamin D and Zinc Status and the Progression of Clinical Symptoms among Outpatients Infected with SARS-CoV-2 and Potentially Non-Infected Participants: A Cross-Sectional Study
	25% more cases (p=0.56). Analysis of vitamin D and zinc levels in 53 PCR+ outpatients and 53 matched controls, showing lower zinc levels in COVID-19 patients, and increased risk of cases and symptoms with vitamin D deficiency. There was no significant difference ..
Aug 26 2021	Golabi et al., Nutrients, doi:10.3390/nu13103368 (date from preprint)	The Association between Vitamin D and Zinc Status and the Progression of Clinical Symptoms among Outpatients Infected with SARS-CoV-2 and Potentially Non-Infected Participants: A Cross-Sectional Study
	90% improved recovery (p<0.0001) and 72% fewer cases (p=0.07). Analysis of vitamin D and zinc levels in 53 PCR+ outpatients and 53 matched controls, showing lower zinc levels in COVID-19 patients, and increased risk of cases and symptoms with vitamin D deficiency. There was no significant difference ..
Aug 25 2021	Varikasuvu et al., Expert Review of Anti-infective Therapy, doi:10.1080/14787210.2022.2035217	COVID-19 and Vitamin D (Co-VIVID Study): a systematic review and meta-analysis of randomized controlled trials
	Meta analysis of 6 vitamin D treatment RCTs, showing statistically significant improvements for pooled outcomes and PCR positivity, and positive but not statistically significant improvements for mortality, mechanical ventilation, ICU adm..
Aug 24 2021	Parra-Ortega et al., Nutrition Research and Practice, doi:10.4162/nrp.2021.15.S1.S32	25-Hydroxyvitamin D level is associated with mortality in patients with critical COVID-19: a prospective observational study in Mexico City
	99% lower mortality (p<0.0001). Prospective study of 94 COVID-19 patients in Mexico, showing lower vitamin D levels associated with mortality in multivariate analysis. 84% of patients were vitamin D deficient, and the remaining 16% had insufficient vitamin D levels.
Aug 20 2021	Song et al., Journal of Biomolecular Structure and Dynamics, doi:10.1080/07391102.2021.1964601	Vitamin D3 and its hydroxyderivatives as promising drugs against COVID-19: a computational study
	In silico study suggesting that vitamin D3 and its biologically active hydroxyderivatives can serve as an TMPRSS2 inhibitor, and inhibit ACE2 binding with the SARS-CoV-2 RBD.
Aug 18 2021	Shakeri et al., Journal of Medical Virology, doi:10.1002/jmv.27277	Evaluation of the relationship between serum levels of zinc, vitamin B12, vitamin D, and clinical outcomes in patients with COVID-19
	Retrospective 293 hospitalized patients in Iran showing lower levels of zinc, vitamin B12, and vitamin D in patients that died, with statistical significance reached only for zinc.
Aug 17 2021	Breslin et al., Proceedings of the Nutrition Society, doi:10.1017/S0029665121002214	The relationship between vitamin D, biomarkers and clinical outcome in hospitalised Covid-19 patients
	56% lower progression (p=0.03). Retrospective 138 COVID-19 hospitalized patients in Ireland, showing increased risk of infiltrates on chest X-ray for patients with vitamin D deficiency, and lower vitamin D levels in patients that died (21.8 nmol/L vs. 37.8 nmol/L, p = 0..
Aug 17 2021	Connolly et al., Proceedings of the Nutrition Society, doi:10.1017/S0029665121002482	An observational study of the association of vitamin D status and other patient characteristics with COVID-19 severity and mortality
	90% lower mortality (p=0.06) and 73% lower need for oxygen therapy (p=0.05). Retrospective 114 hospitalized COVID-19 patients in Ireland, showing higher risk of mortality and oxygen therapy with vitamin D deficiency, with statistical significance for oxygen therapy.
Aug 12 2021	di Filippo et al., The Journal of Clinical Endocrinology & Metabolism, doi:10.1210/clinem/dgab599	Vitamin D levels associate with blood glucose and BMI in COVID-19 patients predicting disease severity
	11% lower mortality (p=1), 42% lower ICU admission (p=0.22), and 40% lower severe cases (p=0.04). Retrospective 88 patients in Italy, showing vitamin D deficiency associated with severe cases, blood glucose, and BMI.
Aug 11 2021	Sinaci et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2021.105964	Impact of vitamin D on the course of COVID-19 during pregnancy: A case control study
	90% lower severe cases (p=0.35) and 19% more moderate/severe cases (p=0.64). Retrospective 159 COVID-19+ pregnant women in Turkey and 332 healthy pregnant controls, showing significantly lower vitamin D levels in COVID-19+ patients. 23% of COVID-19 patients where on vitamin D supplementation, while none of the 7 s..
Aug 10 2021	Alpcan et al., Epidemiology & Infection, doi:10.1017/S0950268821001825	Vitamin D levels in children with COVID-19: a report from Turkey
	73% fewer cases (p=0.0005). Retrospective 75 COVID-19 hospitalized pediatric patients in Turkey and 80 healthy controls, showing significantly lower vitamin D levels in COVID-19 patients.
Aug 5 2021	Eden et al., BMJ Nutrition, Prevention & Health, doi:10.1136/bmjnph-2021-000270	Nutritional parameters and outcomes in patients admitted to intensive care with COVID-19: a retrospective single-centre service evaluation
	64% lower mortality (p=0.1). Retrospective 72 ICU patients in the UK, showing higher mortality with vitamin D deficiency, not reaching statistical significance.
Aug 5 2021	Ribeiro et al., Clinica Chimica Acta, doi:10.1016/j.cca.2021.08.003	Previous vitamin D status and total cholesterol are associated with SARS-CoV-2 infection
	50% fewer cases (p=0.02). Retrospective 1,634 patients tested for SARS-CoV-2 in Brazil, showing vitamin D levels <30ng/mL associated with greater odds of a positive SARS-CoV-2 test in patients older than 49 years.
Aug 5 2021	Nimavat et al., Annals of Medicine and Surgery, doi:10.1016/j.amsu.2021.102661	Vitamin D deficiency and COVID-19: A case-control study at a tertiary care hospital in India
	50% lower mortality (p=0.17) and 68% lower severe cases (p=0.003). Case control study with 156 PCR+ cases in India and 204 controls, showing more frequent vitamin D deficiency in COVID-19 patients, and an association between lower vitamin D levels and COVID-19 severity.
Aug 4 2021	Hosseini et al., Infectious Diseases in Clinical Practice, doi:10.1097/IPC.0000000000001051	Comparing Serum Levels of Vitamin D and Zinc in Novel Coronavirus–Infected Patients and Healthy Individuals in Northeastern Iran, 2020
	Analysis of 56 COVID-19 patients and 46 healthy control patients in Iran, showing that severe cases had lower levels of vitamin D compared with non-severe cases and healthy controls.
Aug 4 2021	Mohseni et al., Nutrition & Food Science, doi:10.1108/NFS-11-2020-0421	Do body mass index (BMI) and history of nutritional supplementation play a role in the severity of COVID-19? A retrospective study
	12% fewer cases (p=0.09). Retrospective 603 patients in Iran, 192 taking vitamin D supplements, showing no significant difference in COVID-19 cases in unadjusted results. IR.SHOUSHTAR.REC.1399.015.
Jul 30 2021	Matin et al., Archives of Microbiology, doi:10.1007/s00203-021-02482-5	The sufficient vitamin D and albumin level have a protective effect on COVID-19 infection
	66% fewer cases (p<0.0001). Case control study with 191 COVID-19 patients and 203 healthy controls in Iran, showing an association between vitamin D deficiency and COVID-19 infection and severity. 84.4% of COVID-19 patients had vitamin D deficiency.
Jul 29 2021	Desai et al., Open Forum Infectious Diseases, doi:10.1093/ofid/ofab408	Vitamin K & D Deficiencies Are Independently Associated With COVID-19 Disease Severity
	Case control study with 100 COVID-19+ patients and 50 age and gender matched controls, showing vitamin K and vitamin D levels independently associated with COVID-19 severity.
Jul 29 2021	Al-Salman et al., Nutrition & Food Science, doi:10.1108/NFS-05-2021-0143	In COVID-19 patients, low 25-hydroxyvitamin D level in serum is associated with longer viral clearance time and higher risk of intensive care unit admission
	44% lower ICU admission (p=0.03). Retrospective 450 hospitalized patients in Bahrain, showing increased risk of ICU admission and slower viral clearance with vitamin D deficiency.
Jul 29 2021	Ghasemian et al., The International Journal of Clinical Practice, doi:10.1111/ijcp.14675	The Role of Vitamin D in the Age of COVID-19: A Systematic Review and Meta-Analysis
	Systematic review and meta analysis of 23 studies, finding significantly higher risk of COVID-19 cases and severity with vitamin D deficiency. Mortality risk was higher with deficiency, but not reaching statistical significance, OR 1.6 [0..
Jul 29 2021	Annweiler et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2021.105958	Vitamin D supplementation prior to or during COVID-19 associated with better 3-month survival in geriatric patients: Extension phase of the GERIA-COVID study
	64% lower mortality (p=0.002). Report on extended results from the GERIA-COVID study, showing significantly lower mortality at 3 months with vitamin D treatment. Results combine prophylaxis and early treatment.
Jul 27 2021	Qayyum et al., Endocrinology and Metabolism, doi:10.1152/ajpendo.00174.2021	Vitamin D and lumisterol novel metabolites can inhibit SARS-CoV-2 replication machinery enzymes
	In silico analysis showing that vitamin D and lumisterol metabolites may inhibit SARS-CoV-2 M^pro and RdRP.
Jul 27 2021	Cozier et al., PLoS ONE, doi:10.1371/journal.pone.0255132	Lower serum 25(OH)D levels associated with higher risk of COVID-19 infection in U.S. Black women
	39% fewer cases (p=0.04). Prospective study of vitamin D levels and COVID-19 infection in the Black Women's Health Study, showing higher risk of infection for lower vitamin D levels. Vitamin D levels were from 3-7 years before infection. Levels at the time of infe..
Jul 27 2021	Israel et al., Epidemiology and Global Health Microbiology and Infectious Disease, doi:10.7554/eLife.68165	Identification of drugs associated with reduced severity of COVID-19: A case-control study in a large population
	13% lower hospitalization (p=0.003). Case control study examining medication usage with a healthcare database in Israel, showing lower risk of hospitalization with vitamin D (defined as being picked up within 35 days prior to PCR+). Other patients may have acquired vitamin D..
Jul 26 2021	Jimenez et al., Nutrients, doi:10.3390/nu13082559	Mortality in Hemodialysis Patients with COVID-19, the Effect of Paricalcitol or Calcimimetics
	50% lower mortality (p=0.02). Retrospective 288 hemodialysis patients in Spain, 137 with existing vitamin D treatments (94 with paricalcitol), showing lower mortality with treatment. There was no significant difference in outcomes based on serum levels, however author..
Jul 23 2021	Güven et al., European Journal of Clinical Nutrition, doi:10.1038/s41430-021-00984-5	The effect of high-dose parenteral vitamin D3 on COVID-19-related inhospital mortality in critical COVID-19 patients during intensive care unit admission: an observational cohort study
	25% lower mortality (p=0.32). Retrospective 175 ICU patients, 113 treated with a single dose of 300,000IU intramuscular cholecalciferol, showing lower mortality with treatment, but not reaching statistical significance. Calcifediol or calcitriol, which avoids several ..
Jul 17 2021	Oristrell et al., Journal of Endocrinological Investigation, doi:10.1007/s40618-021-01639-9	Vitamin D supplementation and COVID-19 risk: a population-based, cohort study
	1% higher mortality (p=0.91) and 1% fewer cases (p=0.65). Retrospective study of cholecalciferol and calcitriol supplementation in Catalonia showing a small but significant lower risk of cases with cholecalciferol, but no significant difference for mortality, or for calcitriol supplementation. S..
Jul 9 2021	Rabail et al., Food Science & Nutrition, doi:10.1002/fsn3.2458	Nutritional and lifestyle changes required for minimizing the recovery period in home quarantined COVID-19 patients of Punjab, Pakistan
	Survey of 80 recovered COVID-19 patients in Pakistan, showing faster recovery with vitamin C, vitamin D, and zinc supplementation.
Jul 7 2021	González-Estevez et al., International Journal of Environmental Research and Public Health, doi:10.3390/ijerph18147266	Association of Food Intake Quality with Vitamin D in SARS-CoV-2 Positive Patients from Mexico: A Cross-Sectional Study
	25% fewer symptomatic cases (p=0.04). Retrospective 40 COVID+ patients in Mexico, showing higher risk of symptoms with vitamin D deficiency. Higher food intake quality and intense physical activity were associated with vitamin D sufficiency. Insufficient intake of several mic..
Jul 7 2021	Hazan et al., medRxiv, doi:10.1101/2021.07.06.21259924	Effectiveness of ivermectin-based multidrug therapy in severely hypoxic, ambulatory COVID-19 patients
	100% lower mortality (p=0.04) and 100% lower hospitalization (p=0.001). Small study of 24 consecutive patients in serious condition (9 days post symptoms, mean SpO₂ 87.4) using combined treatment with ivermectin, doxycycline, zinc, vitamin D, and vitamin C, showing no mortality or hospitalization with treatme..
Jul 6 2021	Margolin et al., Journal of Evidence-Based Integrative Medicine, doi:10.1177/2515690X211026193	20-Week Study of Clinical Outcomes of Over-the-Counter COVID-19 Prophylaxis and Treatment
	94% fewer cases (p=0.003). Retrospective 113 outpatients, 53 (patient choice) treated with zinc, quercetin, vitamin C/D/E, l-lysine, and quina, showing lower cases with treatment. Results are subject to selection bias and limited information on the groups is provid..
Jul 1 2021	Bianconi et al., Nutrition, doi:10.1016/j.nut.2021.111408	Prevalence of vitamin D deficiency and its prognostic impact on patients hospitalized with COVID-19
	18% lower mortality (p=0.59) and 16% lower combined mortality/ICU admission (p=0.53). Prospective study of 200 hospitalized patients in Italy, showing 80% of patients had vitamin D deficiency. There was no significant differences in outcomes based on vitamin D levels. There was also no significant difference in vitamin D l..
Jun 30 2021	Kumar et al., Journal of Cardiovascular Disease Research, 12:6	Association of vitamin D status with severity of COVID-19
	Analysis of 50 COVID-19 hospitalized patients, showing lower vitamin D levels associated with COVID-19 severity.
Jun 30 2021	Nasiri et al., International Journal of Infectious Diseases, doi:10.1016/j.ijid.2021.04.083	Does vitamin D serum level affect prognosis of COVID-19 patients?
	9% higher mortality (p=0.89). Retrospective 329 COVID-19 patients in Iran, showing lower vitamin D levels associated with longer hospitalization, but no significant association with mortality.
Jun 27 2021	Hariyanto et al., Reviews in Medical Virology, doi:10.1002/rmv.2269	Vitamin D supplementation and Covid‐19 outcomes: A systematic review, meta‐analysis and meta‐regression
	63% lower mortality (p=0.0007), 66% lower ventilation (p=0.005), and 73% lower ICU admission (p=0.02). Meta analysis of 11 COVID-19 studies showing lower mortality, mechanical ventilation, and ICU admission with vitamin D. Authors also perform meta-regression showing greater efficacy with increasing age.
Jun 24 2021	Sabico et al., Nutrients, doi:10.3390/nu13072170	Effects of a 2-Week 5000 IU versus 1000 IU Vitamin D3 Supplementation on Recovery of Symptoms in Patients with Mild to Moderate Covid-19: A Randomized Clinical Trial
	14% higher hospital discharge (p=0.14) and 14% faster recovery (p=0.97). Small RCT of 69 hospitalized patients comparing 1,000IU and 5,000IU daily cholecalciferol, showing faster recovery with the higher dose (statistically significant only for cough and ageusia).
Jun 24 2021	Pal et al., Journal of Endocrinological Investigation, doi:10.1007/s40618-021-01614-4	Vitamin D supplementation and clinical outcomes in COVID-19: a systematic review and meta-analysis
	Meta analysis of 13 vitamin D treatment studies, showing significantly lower ICU admission/mortality with treatment.
Jun 24 2021	Beigmohammadi et al., Nutrition, doi:10.1016/j.nut.2021.111400	The association between serum levels of micronutrients and the severity of disease in patients with COVID-19
	Retrospective 60 ICU patients in Iran, showing that lower levels of vitamin D, magnesium, and zinc were significantly associated with higher APACHE scores (P = 0.001, 0.028, and <0.001, respectively) and higher lung involvement (P = 0.002..
Jun 23 2021	Oh et al., Frontiers in Immunology, doi:10.3389/fimmu.2021.594356	Vitamin D and Exercise Are Major Determinants of Natural Killer Cell Activity, Which Is Age- and Gender-Specific
	Analysis of 2,095 patients in South Korea, showing exercise and vitamin D associated with improved natural killer cell activity. [Graydon] showed that a lower frequency of natural killer cells was associated with symptomatic COVID-19 infe..
Jun 22 2021	Zelzer et al., Nutrients, doi:10.3390/nu13072129	Vitamin D Metabolites and Clinical Outcome in Hospitalized COVID-19 Patients
	46% lower mortality (p=0.08). Retrospective 148 patients in Austria, showing no statistically significant differences in vitamin D levels and metabolites for mortality or respiratory support.
Jun 20 2021	Al-Jarallah et al., Journal of Medical Virology, doi:10.1002/jmv.27133	In‐hospital mortality in SARS‐CoV‐2 stratified by serum 25‐hydroxy‐vitamin D levels: A retrospective study
	88% higher mortality (p=0.45). Retrospective 231 hospitalized patients in Kuwait showing no significant difference in mortality based on vitamin D levels.
Jun 17 2021	Jude et al., Journal of Clinical Endocrinology & Metabolism, doi:10.1210/clinem/dgab439	Vitamin D deficiency is associated with higher hospitalisation risk from COVID-19: a retrospective case-control study
	72% lower hospitalization (p<0.0001). Retrospective 80,670 people in the UK with vitamin D levels measured within the last 12 months, showing higher risk of hospitalization with low vitamin D levels.
Jun 14 2021	Campi et al., BMC Infectious Diseases, doi:10.1186/s12879-021-06281-7	Vitamin D and COVID-19 severity and related mortality: a prospective study in Italy
	88% lower severe cases (p<0.0001). Prospective study of 103 hospitalized patients in Italy, showing very high prevalence of vitamin D deficiency, and increased severity for lower vitamin D levels. Vitamin D supplementation was significantly less common for cases.
Jun 9 2021	Herrera-Quintana et al., Nutrients, doi:10.3390/nu13061988	Bad Prognosis in Critical Ill Patients with COVID-19 during Short-Term ICU Stay regarding Vitamin D Levels
	Prospective analysis of 37 critical COVID-19 patients, showing mechanical ventilation associated with lower vitamin D levels.
Jun 7 2021	Dror et al., PLOS ONE, doi:10.1371/journal.pone.0263069 (date from preprint)	Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness
	This paper was retracted.
Jun 6 2021	Diaz-Curiel et al., Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2021.105928	The relationship between 25(OH) vitamin D levels and COVID-19 onset and disease course in Spanish patients
	73% lower ICU admission (p=0.02). Retrospective 1,549 patients in Spain showing that the frequency of vitamin D deficiency was higher in admitted patients compared to the overall Spanish population, and that vitamin D deficiency was associated with increased risk of ICU a..
Jun 4 2021	Kotur et al., Frontiers in Nutrition, doi:10.3389/fnut.2021.689419	Association of Vitamin D, Zinc and Selenium Related Genetic Variants With COVID-19 Disease Severity
	Analysis of variants in genes significant for the status of vitamin D in 120 Serbian COVID-19 patients, showing that vitamin D related genetic variants DHCR7/NADSYN rs12785878 and CYP2R1 rs10741657 were associated with severe COVID-19 in ..
Jun 2 2021	Fasano et al., Movement Disorders, doi:10.1002/mds.28176	COVID-19 in Parkinson’s Disease Patients Living in Lombardy, Italy
	42% fewer cases (p=0.05). Retrospective phone survey of 1,486 Parkinson's disease patients in Italy, showing lower risk of COVID-19 cases with vitamin D supplementation. This paper also presents a case control study of PD patients and family member control patients.
Jun 1 2021	Butler-Laporte et al., PLOS Medicine, doi:10.1371/journal.pmed.1003605	Vitamin D and COVID-19 susceptibility and severity in the COVID-19 Host Genetics Initiative: A Mendelian randomization study
	Mendelian randomization study not finding significant differences in COVID-19 outcomes based on vitamin D level. This study does not compare patients with deficiency/insuffiency/sufficiency, only providing ORs for increase in D levels. Au..
May 31 2021	Pimental et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2021.05.021	Low vitamin D levels and increased neutrophil in patients admitted at ICU with COVID-19
	29% lower mortality (p=1). Retrospective 25 ICU patients in Brazil, showing vitamin D deficiency associated with higher neutrophil-lymphocyte ratio. There appears to be a typo in the mortality percentage for vitamin D deficiency (20% is not valid for the group size..
May 29 2021	Sooriyaarachchi et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2021.05.011	Impact of vitamin D deficiency on COVID-19
	Analysis of vitamin D deficiency and COVID-19 cases and deaths in 47 countries, showing vitamin D deficiency significantly associated with mortality.
May 28 2021	Sánchez-Zuno, Journal of Clinical Medicine, doi:10.3390/jcm10112378	Vitamin D Levels in COVID-19 Outpatients from Western Mexico: Clinical Correlation and Effect of Its Supplementation
	89% lower severe cases (p=0.04) and 81% improved recovery (p=0.22). Very small 42 PCR+ outpatient RCT in Mexico, 22 treated with vitamin D. Most patients had insufficient vitamin D levels, there were more symptoms in those with insufficient levels, and there were less cases with fever or with >3 symptoms ..
May 28 2021	Galaznik et al., Journal of Clinical Oncology, doi:10.1200/JCO.2021.39.15_suppl.6589	Assessment of vitamin D deficiency and COVID-19 diagnosis in patients with breast or prostate cancer using electronic medical records
	35% fewer cases (p=0.01). Retrospective 16,287 breast cancer and 14,919 prostate cancer showing increased risk of COVID-19 cases with vitamin D deficiency.
May 26 2021	Al-Mazaideh et al., Journal of Pharmaceutical Research International, doi:10.9734/jpri/2021/v33i29B31603	Vitamin D is a New Promising Inhibitor to the Main Protease (Mpro) of COVID-19 by Molecular Docking
	In silico study showing vitamin D binding with M^pro of SARS-CoV-2. Among the compounds tested, vitamin D had the highest potential interaction in terms of total H-bond, van der Waal, torsional, and desolvation energy. Authors recommend ad..
May 25 2021	Papadimitriou et al., World J. Virology, doi:10.5501/wjv.v10.i3.111]	Association between population vitamin D status and SARS-CoV-2 related serious-critical illness and deaths: An ecological integrative approach
	Country analysis showing negative correlations between population vitamin D level and severe cases and death (but not with cases overall). Authors conclude that higher vitamin D levels may protect from severe cases and death, even more so..
May 22 2021	Asimi et al., Endocrine Abstracts, doi:10.1530/endoabs.73.PEP14.2	Selenium, zinc, and vitamin D supplementation affect the clinical course of COVID-19 infection in Hashimoto’s thyroiditis
	97% lower ventilation (p<0.0001), 99% lower hospitalization (p<0.0001), and 100% lower severe cases (p<0.0001). Retrospective 356 Hashimoto's thyroiditis outpatients, 270 taking vitamin D, zinc, and selenium, showing significantly lower hospitalization with treatment. Authors adjust for age, gender, BMI, and smoking status, reporting statistically ..
May 21 2021	Reis et al., The American Journal of Clinical Nutrition, doi:10.1093/ajcn/nqab151	Influence of vitamin D status on hospital length of stay and prognosis in hospitalized patients with moderate to severe COVID-19: a multicenter prospective cohort study
	23% lower mortality (p=0.82), 45% higher ventilation (p=0.77), 33% higher hospital discharge (p=0.18), and 22% shorter hospitalization (p=0.06). Prospective study of 220 hospitalized patients in Brazil, showing no significant differences based on vitamin D levels. There was a trend (p=0.057) towards longer hospital stay for patients with levels <10ng/mL.
May 21 2021	Alcala-Diaz et al., Nutrients, doi:10.3390/nu13061760	Calcifediol Treatment and Hospital Mortality Due to COVID-19: A Cohort Study
	81% lower mortality (p=0.04). Retrospective 537 patients in Spain, 79 treated with calcifediol, showing significantly lower mortality with treatment. The treated group had a higher risk of comorbidity, whereas the control group had lower O2 saturation, higher CURB-65,..
May 19 2021	AlSafar et al., Nutrients, doi:10.3390/nu13051714	COVID-19 Disease Severity and Death in Relation to Vitamin D Status among SARS-CoV-2-Positive UAE Residents
	59% lower mortality (p=0.05) and 33% lower severe cases (p=0.005). Retrospective 464 patients in United Arab Emirates showing low D levels at first hospital visit associated with higher COVID-19 severity and mortality.
May 19 2021	Li et al., JAMA Network Open, doi:10.1001/jamanetworkopen.2021.11634	Assessment of the Association of Vitamin D Level With SARS-CoV-2 Seropositivity Among Working-Age Adults
	9% fewer cases (p=0.24). Cohort study of 18,148 patients in the USA showing low vitamin D associated with COVID-19 PCR+ status before adjustments but not after. Authors state that "low vitamin D levels were not independently associated with the risk of..
May 18 2021	Davoudi et al., BMC Infectious Diseases, doi:10.1186/s12879-021-06168-7	Lack of association between vitamin D insufficiency and clinical outcomes of patients with COVID-19 infection
	12% higher mortality (p=1), 16% lower ventilation (p=1), 28% lower ICU admission (p=0.74), and 68% higher severe cases (p=0.3). Retrospective 153 hospitalized patients in Iran, showing no significant difference in outcomes based on vitamin D levels. Adjusted results are only provided for vitamin D as a continuous variable.
May 18 2021	Dudley et al., BJPsych Bulletin, doi:10.1192/bjb.2021.55	Revisiting vitamin D status and supplementation for in-patients with intellectual and developmental disability in the North of England, UK
	22% fewer symptomatic cases (p=0.65). Retrospective 64 patients with intellectual and developmental disability in the UK, showing no significant difference in COVID-19 status with vitamin D supplementation. Only 6 patients were not on vitamin D supplementation.
May 11 2021	Aldwihi et al., International Journal of Environmental Research and Public Health, doi:10.3390/ijerph18105086	Patients’ Behavior Regarding Dietary or Herbal Supplements before and during COVID-19 in Saudi Arabia
	49% higher hospitalization (p=0.002). Retrospective survey-based analysis of 738 COVID-19 patients in Saudi Arabia, showing lower hospitalization with vitamin C, turmeric, zinc, and nigella sativa, and higher hospitalization with vitamin D. For vitamin D, most patients contin..
May 8 2021	Savitri et al., Annals of the Romanian Society for Cell Biology, 25:6	Comparison between Vitamin D Level of Asymptomatic Confirmed Covid-19 Patients with Symptomatic Confirmed Covid-19 Patients in Makassar
	88% fewer symptomatic cases (p<0.0001). Retrospective 42 PCR+ patients in Indonesia, showing significantly higher risk of symptomatic cases with vitamin D deficiency.
May 7 2021	Bychinin et al., Journal of Clinical Practice, doi:10.17816/clinpract64976	Prevalence of hypovitaminosis D in COVID-19 patients in the intensive care unit
	36% lower mortality (p=0.03). Retrospective 103 COVID-19 ICU patients in Russia, showing higher mortality with low vitamin D levels in unadjusted results.
May 3 2021	Levitus et al., Journal of the Endocrine Society, doi: 10.1210/jendso/bvab048.567	The Effect of Vitamin D Supplementation on Severe COVID-19 Outcomes in Patients With Vitamin D Insufficiency
	31% lower severe cases (p=0.25). Retrospective 129 hospitalized patients with vitamin D levels measured within 90 days prior to admission, showing lower, but not statistically significant, risk of severe cases with vitamin D supplementation among patients with levels <20..
May 3 2021	Shaw Stewart et al., Reviews in Medical Virology, doi:10.1002/rmv.2241	Temperature dependent viral tropism: understanding viral seasonality and pathogenicity as applied to the avoidance and treatment of endemic viral respiratory illnesses
	Review and hypothesis article proposing Temperature Dependent Viral Tropism (TDVT) to explain the seasonality, geographic distribution, and epidemic dynamics of respiratory viral illnesses, including COVID-19.
Apr 30 2021	Elhadi et al., PLOS ONE, doi:10.1371/journal.pone.0251085	Epidemiology, outcomes, and utilization of intensive care unit resources for critically ill COVID-19 patients in Libya: A prospective multi-center cohort study
	23% lower mortality (p=0.29). Prospective study of 465 COVID-19 ICU patients in Libya showing no significant differences with treatment.
Apr 30 2021	Azadeh et al., J. Mazandaran Univ. Med. Sci. 31:195	Serum Vitamin D Concentrations in CoVID19 Patients
	Retrospective 80 COVID-19 patients in Iran and 70 healthy controls, showing significantly lower vitamin D levels in COVID-19 patients.
Apr 29 2021	Loucera et al., Scientific Reports, doi:10.1038/s41598-021-02701-5 (date from preprint)	Real world evidence of calcifediol or vitamin D prescription and mortality rate of COVID-19 in a retrospective cohort of hospitalized Andalusian patients
	33% lower mortality (p=0.009). Retrospective 15,968 hospitalized patients in Spain showing a significant reduction in mortality associated with the prescription of vitamin D, especially calcifediol, within 15-30 days prior to hospitalization.
Apr 26 2021	Al-Daghri et al., Journal of Translational Medicine, doi:10.1186/s12967-021-02838-x	Vitamin D status of Arab Gulf residents screened for SARS-CoV-2 and its association with COVID-19 infection: a multi-centre case–control study
	Case control study with 220 adults showing significantly lower vitamin D levels in PCR+ patients.
Apr 18 2021	Elham et al., Clinical Nutrition ESPEN, doi:10.1016/j.clnesp.2021.03.040	Serum vitamin D, calcium, and zinc levels in patients with COVID-19
	Case control study with 93 hospitalized patients in Iran and 186 control patients, showing significantly lower vitamin D, zinc, and calcium levels in cases. IR.SHOUSHTAR.REC.1399.017.
Apr 17 2021	Shah Alam et al., International Immunopharmacology, doi:10.1016/j.intimp.2021.107686	The role of vitamin D in reducing SARS-CoV-2 infection: An update
	Review of vitamin D for COVID-19 noting that infections are likely to be more prevalent in the winter season; clinical trials show vitamin D as a potential therapeutic agent; vitamin D is beneficial against COVID-19 by reducing inflammato..
Apr 8 2021	Abdulateef et al., Open Medicine, doi:10.1515/med-2021-0273	COVID-19 severity in relation to sociodemographics and vitamin D use
	41% lower hospitalization (p=0.3). Survey of 428 recovered COVID-19 patients in Iraq, showing fewer hospital visits for patients on prophylactic vitamin C or D. Hospitalization was lower for those on vitamin C, D, or zinc, without statistical significance. The study observ..
Apr 6 2021	Oristrell et al., Biomedicines, doi:10.3390/biomedicines9050509 (date from preprint)	Association of Calcitriol Supplementation with Reduced COVID-19 Mortality in Patients with Chronic Kidney Disease: A Population-based Study
	43% lower mortality (p=0.001), 43% lower severe cases (p=0.0008), and 22% fewer cases (p=0.01). Retrospective study of calcitriol supplementation with chronic kidney disease patients in Catalonia showing lower cases, severe cases, and mortality with supplementation. A dose-response relationship was found for severe cases and mortali..
Apr 5 2021	Ünsal et al., Journal of Endocrinological Investigation, doi:10.1007/s40618-021-01566-9	Retrospective analysis of vitamin D status on ınflammatory markers and course of the disease in patients with COVID-19 infection
	81% lower mortality (p=0.23) and 73% lower need for oxygen therapy (p=0.07). Retrospective 56 patients in Turkey showing greater need for oxygen therapy and higher mortality with vitamin D deficiency, and significantly lower risk of pneumonia with vitamin D supplementation.
Apr 2 2021	Livingston et al., Int. J. Clinical Practive, doi:10.1111/ijcp.14166	Detectable respiratory SARS-CoV-2 RNA is associated with low vitamin D levels and high social deprivation
	51% fewer cases (p=0.02). Retrospective 104 consecutive patients tested for COVID-19 in a hospital in the UK, showing lower vitamin D and higher social deprivation associated with COVID-19 positive results.
Mar 31 2021	Bayramoğlu et al., European Journal of Pediatrics, doi:10.1007/s00431-021-04030-1	The association between vitamin D levels and the clinical severity and inflammation markers in pediatric COVID-19 patients: single-center experience from a pandemic hospital
	70% lower severe cases (p=0.03). Retrospective 103 pediatric hospitalized COVID-19 patients, showing an association between vitamin D deficiency and clinical severity.
Mar 31 2021	Griffin et al., Clinical Medicine, doi:10.7861/clinmed.2021-0035	Perspective: Vitamin D supplementation prevents rickets and acute respiratory infections when given as daily maintenance but not as intermittent bolus: implications for COVID-19
	Review of evidence showing that low-dose daily vitamin D supplementation is more effective than intermittent high-dose bolus for preventing various conditions, with a plausible biological mechanism. Bolus treatment may be less effective t..
Mar 30 2021	Holt et al., Thorax, doi:10.1136/thoraxjnl-2021-217487	Risk factors for developing COVID-19: a population-based longitudinal study (COVIDENCE UK)
	7% fewer cases (p=0.53). Prospective survey-based study with 15,227 people in the UK, showing lower risk of COVID-19 cases with vitamin A, vitamin D, zinc, selenium, probiotics, and inhaled corticosteroids; and higher risk with metformin and vitamin C. Statistica..
Mar 29 2021	Akbar et al., Front. Nutr. 8:660420, doi:10.3389/fnut.2021.660420	Low Serum 25-hydroxyvitamin D (Vitamin D) Level Is Associated With Susceptibility to COVID-19, Severity, and Mortality: A Systematic Review and Meta-Analysis
	Systematic review and meta analysis showing that low vitamin D levels was associated with COVID-19 cases, severity, and mortality.
Mar 27 2021	Gaudio et al., International Journal of Environmental Research and Public Health, doi:10.3390/ijerph18073491	Vitamin D Levels Are Reduced at the Time of Hospital Admission in Sicilian SARS-CoV-2-Positive Patients
	79% fewer cases (p<0.0001). Retrospective 50 COVID-19 hospitalized patients in Italy with vitamin D levels measured on admission, and 100 matched control patients, showing significantly lower vitamin D levels in COVID-19 patients. Vitamin D levels were also lower in..
Mar 27 2021	Freitas et al., medRxiv, doi:10.1101/2021.03.22.21254032	Vitamin D-related polymorphisms and vitamin D levels as risk biomarkers of COVID-19 infection severity
	41% lower mortality (p=0.02). Analysis of 491 hospitalized patients in Portugal showing that polymorphisms in the vitamin D binding protein encoded by the GC gene are related to COVID-19 severity (p = 0.005). There was an association between vitamin D polygenic risk s..
Mar 26 2021	Petrelli et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2021.105883	Therapeutic and prognostic role of vitamin D for COVID-19 infection: A systematic review and meta-analysis of 43 observational studies
	59% lower mortality (p=0.01) and 73% lower severe cases (p=0.004). Meta analysis showing vitamin D deficiency associated with higher risk of COVID-19, worse severity, and higher mortality. Supplementation with vitamin D reduced the risk of severe cases and mortality.
Mar 22 2021	Kohlmeier et al., BMJ Nutrition, Prevention & Health, doi:10.1136/bmjnph-2021-000265	When Mendelian randomisation fails
	Analysis of why Mendelian randomization may fail in vitamin D studies. Authors suggest that it may come down to the use of 25(OH)D concentration in serum as a less than ideal proxy for vitamin D status of cells involved in the immune resp..
Mar 19 2021	Meltzer et al., JAMA Netw Open., doi:10.1001/jamanetworkopen.2021.4117	Association of Vitamin D Levels, Race/Ethnicity, and Clinical Characteristics With COVID-19 Test Results
	35% fewer cases (p=0.11). Retrospective 4,638 individuals with vitamin D levels within 1 year before COVID-19 testing, showing higher risk of COVID-19 PCR+ for vitamin D deficient individuals, and lower (but not statistically significant) cases for individuals usi..
Mar 15 2021	Pugach et al., Wiener klinische Wochenschrift, doi:10.1007/s00508-021-01833-y	Strong correlation between prevalence of severe vitamin D deficiency and population mortality rate from COVID-19 in Europe
	Analysis of COVID-19 in European countries, finding a correlation between the prevalence of severe vitamin D deficiency and the mortality rate.
Mar 14 2021	Vanegas-Cedillo et al., medRxiv, doi:10.1101/2021.03.12.21253490	Serum Vitamin D Levels Are Associated With Increased COVID-19 Severity and Mortality Independent of Whole-Body and Visceral Adiposity
	53% lower mortality (p=0.006). Retrospective 551 moderate to severe COVID-19 patients in Mexico showing vitamin D ≤12ng/mL independently associated with COVID-19 mortality. No association was found between vitamin D levels and the need for intubation. Vitamin D deficie..
Mar 13 2021	Jayawardena et al., Diabetes & Metabolic Syndrome: Clinical Research & Reviews, doi:10.1016/j.dsx.2021.03.006	Impact of the vitamin D deficiency on COVID-19 infection and mortality in Asian countries
	Analysis of Asian countries finding that prevalence of vitamin D deficiency and lower vitamin D levels were associated with COVID-19 infection and mortality. Positive correlations were observed for prevalence of vitamin D deficiency with ..
Mar 12 2021	Ahmad et al., Nutrients, doi:10.3390/nu15224818 (date from preprint)	Association between Average Vitamin D Levels and COVID-19 Mortality in 19 European Countries—A Population-Based Study
	21% lower mortality (p=0.01). Analysis of 19 European countries showing significantly lower mortality with higher vitamin D levels.
Mar 9 2021	Nikniaz et al., Pharmaceutical Sciences, doi:10.34172/PS.2021.13	The impact of vitamin D supplementation on mortality rate and clinical outcomes of COVID-19 patients: A systematic review and meta-analysis
	74% lower mortality (p=0.008). Meta analysis of 4 supplementation studies, finding that vitamin D supplementation "seems to decrease the mortality rate, the severity of the disease, and serum levels of the inflammatory markers". Mortality odds ratio OR 0.264,..
Mar 8 2021	Charoenngam et al., Endocrine Practice, doi:10.1016/j.eprac.2021.02.013	Association of vitamin D status with hospital morbidity and mortality in adult hospitalized COVID-19 patients
	34% lower mortality (p=0.26), 37% lower ventilation (p=0.17), and 23% lower ICU admission (p=0.28). Retrospective 287 hospitalized patients in the USA showing significantly lower mortality with vitamin D sufficiency in elderly patients and patients without obesity; and lower mortality for all patients but not reaching statistical signif..
Mar 7 2021	Notz et al., Clinical Nutrition, doi:10.1016/j.clnu.2021.03.001	Vitamin D deficiency in critically ill COVID-19 ARDS patients
	Retrospective 26 ICU patients showing that the majority of patients had vitamin D deficiency. There was no statistically significant association of 25-hydroxyvitamin D status and clinical course, however low levels of 1,25-dihydroxyvitami..
Mar 5 2021	Kralj et al., Critical Case Reports, doi:10.1002/ccr3.4010	Vitamin D and COVID-19 in an immunocompromised patient with multiple comorbidities—A Case Report
	Case report of a high-risk immunocompromised patient with multiple comorbidities that had a mild case of COVID-19. The patient had UVB phototherapy three months earlier and had normal vitamin D levels (92.2 nmol/L, normal range 50-125).
Mar 5 2021	Mazziotti et al., Journal of Endocrinological Investigation, doi:10.1007/s40618-021-01535-2	Vitamin D deficiency, secondary hyperparathyroidism and respiratory insufficiency in hospitalized patients with COVID-19
	19% lower mortality (p=0.49) and 67% higher ventilation (p=0.08). Retrospective 348 hospitalized patients in Italy showing vitamin D deficiency associated with acute hypoxemic respiratory failure. Vitamin D supplementation during hospitalization was not significantly associated with mortality or ventila..
Mar 4 2021	Ullah et al., Pancreatology, doi:10.1016/j.pan.2020.10.005	COVID-19 in patients with hepatobiliary and pancreatic diseases in East London: a single-centre cohort study
	42% higher mortality (p=0.35) and 146% more cases (p<0.0001). Retrospective 15,440 patients with hepatobiliary and pancreatic diseases in the United Kingdom, 226 with confirmed COVID-19, showing higher risk with vitamin D supplementation. Results are likely confounded by impaired vitamin D processin..
Mar 4 2021	Lohia et al., American Journal of Physiology-Endocrinology and Metabolism, doi:10.1152/ajpendo.00517.2020	Exploring the link between vitamin D and clinical outcomes in COVID-19
	15% lower mortality (p=0.56), 19% lower ventilation (p=0.48), and 28% lower ICU admission (p=0.17). Retrospective 270 patients with vitamin D levels measured in the last year, showing no significant difference in outcomes based on vitamin D levels or vitamin D supplementation.
Mar 3 2021	Ricci et al., Respiratory Research, doi:10.1186/s12931-021-01666-3	Circulating Vitamin D levels status and clinical prognostic indices in COVID-19 patients
	88% lower mortality (p=0.07). Retrospective 52 hospitalized COVID-19 patients showing that vitamin D deficiency is associated with compromised inflammatory responses and higher pulmonary involvement. Vitamin D deficient patients also showed higher mortality, although ..
Feb 28 2021	Karen et al., International Journal of Progressive Science and Technologies, doi:10.52155/ijpsat.v27.2.3269	Vitamin D Associated Peculiarities in Women with Mild Covid-19 and Effect of Calcifediol on the Level of Vitamin D and Possibly, on Disease Outcome - Prospective Pilot Study
	Prospective study of 30 female COVID-19 patients, all treated with calcifediol on admission, showing significantly increased vitamin D levels with treatment. There was no mortality.
Feb 24 2021	Sulli et al., Nutrients, doi:10.3390/nu13030717	Vitamin D and Lung Outcomes in Elderly COVID-19 Patients
	76% fewer cases (p=0.0002). Retrospective 65 elderly COVID-19 patients and 65 matched controls, showing lower vitamin D levels associated with more severe lung involvement, longer disease duration, and higher mortality. Vitamin D supplementation was less common in t..
Feb 19 2021	Gavioli et al., Journal of the American College of Nutrition, doi:10.1080/07315724.2020.1869626	An Evaluation of Serum 25-Hydroxy Vitamin D Levels in Patients with COVID-19 in New York City
	5% higher mortality (p=0.83), 55% lower need for oxygen therapy (p=0.0002), and 4% lower hospitalization (p=0.41). Retrospective 437 mostly serious condition (85% hospitalized) patients in New York, showing vitamin D deficiency associated with increased likelihood of oxygen support, but no association with mortality and hospitalization. Multivariate a..
Feb 18 2021	Infante et al., Journal of the American College of Nutrition, doi:10.1080/07315724.2021.1877580	Low Vitamin D Status at Admission as a Risk Factor for Poor Survival in Hospitalized Patients With COVID-19: An Italian Retrospective Study
	55% lower mortality (p=0.05). Retrospective 137 hospitalized patients in Italy. All patients had low vitamin D levels, and lower levels were associated with higher mortality. In multivariate logistic regression, vitamin D levels were significantly inversely associated..
Feb 17 2021	Burahee et al., SICOT-J, doi:10.1051/sicotj/2021001	Older patients with proximal femur fractures and SARS-CoV-2 infection – An observational study
	93% lower mortality (p=0.01). Small retrospective study of 29 hip fracture patients in the UK, 14 with COVID-19. All COVID-19 patients were treated with vitamin D except for 2 where testing and supplementation was missed due to a clerical error. The two COVID-19 patie..
Feb 12 2021	Basaran et al., Bratislava Medical Journal, doi:10.4149/bll_2021_034	The relationship between vitamin D and the severity of COVID-19
	69% lower severe cases (p=0.005). Prospective study of 204 patients with COVID-19-like pneumonia in Turkey, 42 outpatients (mild cases), and 162 inpatients (serious cases), showing significantly higher risk of severe cases with vitamin D deficiency.
Feb 12 2021	Susianti et al., Journal of Medical Biochemistry, doi:10.5937/jomb0-30228	Low levels of vitamin D were associated with coagulopathy among hospitalized coronavirus disease-19 (COVID-19) patients: A single-centered study in Indonesia
	91% lower mortality (p=0.32), 90% lower ICU admission (p=0.32), and 81% lower progression (p=0.04). Retrospective 50 hospitalized PCR+ patients in Indonesia showing ICU admission, mortality, ISTH DIC (Disseminated Intravascular Coagulation) score ≥5, and increased D-dimer significantly associated with lower vitamin D levels.
Feb 9 2021	Hancock et al., SSRN, doi:10.2139/ssrn.3779211	Case Cluster of RT-PCR COVID-19 Positive Patients with an Unexpected Benign Clinical Course With Vitamin D, Melatonin, Vitamin C, and Viscum Album
	Case series of 24 COVID-19 patients (12 confirmed PCR+) treated with vitamin D, vitamin C, and melatonin, showing positive outcomes with no patient having worse than a mild case, including 7 high risk patients.
Feb 8 2021	Ersöz et al., International Journal of Clinical Practice, doi:10.1111/ijcp.14078	The association between micronutrient and hemogram values and prognostic factors in COVID-19 patients: A single-center experience from Turkey
	Retrospective 310 hospitalized COVID-19 patients in Turkey, showing patients that were admitted to the ICU, intubated, or died had lower vitamin D levels compared to those that were not (statistically significant for ICU admission).
Feb 3 2021	Yadav et al., Indian Journal of Clinical Biochemistry, doi:10.1007/s12291-020-00950-1	Association of Vitamin D Status with COVID-19 Infection and Mortality in the Asia Pacific region: A Cross-Sectional Study
	Analysis of vitamin D levels and COVID-19 in 37 Asia Pacific countries, finding a significant association with the number of cases/million (r = -0.394, p = 0.016) and a weak association with the number of deaths/ million (r = -0.280, p = ..
Feb 2 2021	Söbü et al., The Journal of Current Pediatrics, doi:10.4274/jcp.2021.0002	Vitamin D Levels of COVID-19 Positive Sypmtomatic Pediatric Cases
	Retrospective 30 hospitalized pediatric COVID-19 patients and 82 healthy controls, showing significantly lower vitamin D levels in COVID-19 patients.
Feb 1 2021	Patchen et al., BMJ Nutrition, Prevention & Health, doi:10.1136/bmjnph-2021-000255	Genetically predicted serum vitamin D and COVID-19: a Mendelian randomization study
	2% lower severe cases (p=0.11), no change in hospitalization (p=1), and no change in cases (p=1). UK Biobank Mendelian randomization study not finding significant differences in COVID-19 risk. The number of people predicted to have vitamin D deficiency does not appear to be provided.
Jan 31 2021	Nadiger et al., Critical Care Medicine, doi:10.1097/01.ccm.0000726440.30551.47	Vitamin D Levels in Children With COVID-19 Admitted to the PICU
	Retrospective 14 pediatric COVID-19 ICU patients showing that the majority were vitamin D deficient.
Jan 29 2021	Demir et al., Journal of Medical Virology, doi:10.1002/jmv.26832	Vitamin D deficiency is associated with COVID-19 positivity and the severity of the disease
	89% lower severe cases (p=0.001), 87% shorter hospitalization (p=0.001), and 24% fewer cases (p=0.18). Retrospective cohort study of 487 patients finding that lower vitamin D levels is associated with more severe cases as measured by affected lung segments and increased hospitalization time for COVID-19 positive patients, and that lower vi..
Jan 29 2021	Ma et al., The American Journal of Clinical Nutrition, doi:10.1093/ajcn/nqaa381	Habitual use of vitamin D supplements and risk of coronavirus disease 2019 (COVID-19) infection: a prospective study in UK Biobank
	30% fewer cases (p=0.03). Retrospective 8,297 adults from the UK Biobank showing the habitual use of vitamin D supplements significantly associated with lower risk of COVID-19 cases. Note that the information on vitamin D supplement use was collected a median of 1..
Jan 29 2021	Bakaloudi et al., Nutrition, doi:10.1016/j.nut.2021.111441	A critical update on the role of mild and serious vitamin D deficiency prevalence and the COVID-19 epidemic in Europe
	Analysis of vitamin D deficiency and COVID-19 cases and mortality in European countries showing significant correlation between mortality and prevalence of both mild vitamin D deficiency (r = 0.634, p = 0.003) and severe vitamin D deficie..
Jan 28 2021	Brenner, H., Nutrients, doi:10.3390/nu13020411	Vitamin D Supplementation to Prevent COVID-19 Infections and Deaths—Accumulating Evidence from Epidemiological and Intervention Studies Calls for Immediate Action
	Summary of epidemiological and intervention studies for vitamin D supplementation. Author concludes that despite limitations, evidence strongly supports widespread supplementation, in particular for high-risk populations, as well as high-..
Jan 25 2021	Tehrani et al., Clinical Nutrition, doi:10.1016/j.clnesp.2021.01.014	Evaluation of vitamin D levels in COVID-19 patients referred to Labafinejad hospital in Tehran and its relationship with disease severity and mortality
	48% lower mortality (p=0.07). Retrospective 205 patients in Iran, showing higher mortality with vitamin D deficiency, not quite reaching statistical significance.
Jan 25 2021	Barassi et al., Panminerva Med., doi:10.23736/S0031-0808.21.04277-4	Vitamin D in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients with non-invasive ventilation support
	65% lower ventilation (p=0.15). Retrospective 118 consecutive hospitalized PCR+ patients in Italy showing higher ventilation and mortality with vitamin D deficiency.
Jan 22 2021	Nogués et al., The Journal of Clinical Endocrinology & Metabolism, doi:10.1210/clinem/dgab405 (date from preprint)	Calcifediol Treatment and COVID-19-Related Outcomes
	79% lower mortality (p=0.001) and 87% lower ICU admission (p<0.0001). Quasi-randomized trial with 930 hospitalized patients, 447 treated with calcifediol, showing significantly lower ICU admission and death with treatment. Note that the randomization in this trial is by ward. Authors report that patients we..
Jan 21 2021	Walrand, S., Nature, doi:10.1038/s41598-021-81419-w	Autumn COVID-19 surge dates in Europe correlated to latitudes, not to temperature-humidity, pointing to vitamin D as contributing factor
	Analysis of the increase in COVID-19 cases in European countries, showing no correlation with temperature, but a significant correlation with country latitude. Since UV radiation decreases earlier for higher latitudes, this supports the t..
Jan 19 2021	Abioye et al., BMJ Global Health, doi:10.1136/bmjgh-2020-003176	Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: a systematic review and meta-analysis
	Systematic review and meta-analysis of 80 randomized controlled trials showing reduced risk of acute respiratory infections with vitamin C and vitamin D, and shorter duration of symptoms with vitamin C, vitamin D, and zinc.
Jan 19 2021	Orchard et al., Clin Chem Lab Med, doi:10.1515/cclm-2020-1567	Vitamin-D levels and intensive care unit outcomes of a cohort of critically ill COVID-19 patients
	59% lower ICU admission (p=0.001) and 9% lower ventilation (p=0.7). Retrospective 165 hospitalized patients with known vitamin D levels, showing an associated between vitamin D deficiency and ICU admission. There was no statistically significant difference in clinical outcomes for ICU patients. It's uncle..
Jan 18 2021	Vasheghani et al., Scientific Reports, doi:10.1038/s41598-021-97017-9 (date from preprint)	The relationship between serum 25-hydroxyvitamin D levels and the severity of COVID-19 disease and its mortality
	30% lower mortality (p=0.45) and 64% lower ICU admission (p=0.009). Retrospective 508 hospitalized COVID-19 patients in Iran showing lower mortality with vitamin D supplementation (not reaching statistical significance), and an association between lower vitamin D levels and disease severity, ICU admission..
Jan 16 2021	Hutchings et al., Endocrine, doi:10.1007/s12020-020-02597-7	Patients hospitalized with COVID-19 have low levels of 25-hydroxyvitamin D
	Retrospective 330 hospitalized COVID-19 patients in Armenia, showing significantly higher prevalence of vitamin D deficiency (<12ng/mL) compared to health controls (45% vs. 13%).
Jan 14 2021	Giannini et al., Nutrients, doi:10.3390/nu13010219	Effectiveness of In-Hospital Cholecalciferol Use on Clinical Outcomes in Comorbid COVID-19 Patients: A Hypothesis-Generating Study
	37% lower combined mortality/ICU admission (p=0.13). Retrospective 91 hospitalized patients, 36 treated with high-dose cholecalciferol, showing lower combined death/ICU admission with treatment. Authors also analyze the relationship with comorbidity burden, finding that the positive effect ..
Jan 12 2021	Bennouar et al., Journal of the American College of Nutrition, doi:10.1080/07315724.2020.1856013	Vitamin D Deficiency and Low Serum Calcium as Predictors of Poor Prognosis in Patients with Severe COVID-19
	86% lower mortality (p=0.002). Prospective study of 120 severe cases of COVID-19 in Algeria finding low vitamin D and low calcium both associated with increased mortality.
Jan 11 2021	Li et al., Aging and Disease, doi:10.14336/AD.2020.1108	Metabolic Healthy Obesity, Vitamin D Status, and Risk of COVID-19
	36% lower hospitalization (p<0.0001) and 29% fewer cases (p<0.0001). UK Biobank retrospective 353,299 patients showing that vitamin D insufficiency and deficiency are associated with increased COVID-19 risk. This study also analyzes metabolic/obesity phenotypes and the combination with vitamin D status. No..
Jan 9 2021	Angelidi et al., Mayo Clinic Proceedings, doi:10.1016/j.mayocp.2021.01.001	Vitamin D Status is Associated With In-hospital Mortality and Mechanical Ventilation: A Cohort of COVID-19 Hospitalized Patients
	88% lower mortality (p=0.01). Retrospective 144 patients in the USA showing significantly lower mortality for vitamin D levels ≥30ng/mL.
Jan 7 2021	Pal et al., Frontiers in Medicine, doi:10.3389/fmed.2020.590805	High Prevalence of Hypocalcemia in Non-severe COVID-19 Patients: A Retrospective Case-Control Study
	Retrospective 72 non-severe COVID-19 patients in India, showing very high levels of vitamin D deficiency (70 of 72 patients).
Jan 7 2021	Amin et al., BMJ Nutrition, Prevention & Health, doi:10.1136/bmjnph-2020-000151	No evidence that vitamin D is able to prevent or affect the severity of COVID-19 in individuals with European ancestry: a Mendelian randomisation study of open data
	32% higher progression (p=0.2) and 8% more cases (p=0.14). Analysis of vitamin D levels and COVID-19 cases and severity based on genetic predisposition to higher vitamin D levels or lower vitamin D deficiency, finding no significant association.
Dec 31 2020	Ansari et al., Pakistan J. Med. Heal. Sci., 14:4	Frequency of Severe Vitamin D Deficiency and its Association with Mortality in Patients with Corona virus Disease
	86% lower mortality (p=0.02). Prospective study of 125 severe COVID-19 patients in Pakistan, showing significantly higher mortality with vitamin D deficiency.
Dec 31 2020	Karonova et al., Infectology, doi:10.22625/2072-6732-2020-12-3-21-27	Serum 25(oH)D level in patients with CoVID-19
	79% lower mortality (p=0.11) and 71% lower severe cases (p=0.05). Retrospective 80 COVID-19 patients showing low vitamin D levels associated with severity and mortality.
Dec 30 2020	Szeto et al., Endocrine Research, doi:10.1080/07435800.2020.1867162	Vitamin D Status and COVID-19 Clinical Outcomes in Hospitalized Patients
	6% higher mortality (p=1), 40% lower ventilation (p=0.21), and 27% lower hospital discharge (p=0.5). Retrospective 93 hospitalized patients with vitamin D levels 1-365 days before admission, not showing significant differences with vitamin D deficiency or vitamin D levels. Vitamin D levels may vary significantly throughout the year creat..
Dec 30 2020	McCullough et al., Reviews in Cardiovascular Medicine, doi:10.31083/j.rcm.2020.04.264	Multifaceted highly targeted sequential multidrug treatment of early ambulatory high-risk SARS-CoV-2 infection (COVID-19)
	Review urging early treatment of COVID-19 with sequential multidrug treatment that has been shown to be safe and effective. Proposed treatment includes zinc, vitamin D & C, quercetin, and depending on age, comorbidities, and symptoms may ..
Dec 28 2020	Jevalikar et al., Scientific Reports, doi:10.1038/s41598-021-85809-y (date from preprint)	Lack of association of baseline 25-hydroxyvitamin D levels with disease severity and mortality in Indian patients hospitalized for COVID-19
	82% lower mortality (p=0.12), 34% lower ICU admission (p=0.29), and 32% lower need for oxygen therapy (p=0.06). Prospective study of 410 hospitalized patients in India showing lower mortality and ICU admission with cholecalciferol treatment, although not statistically significant with the small number of cases. The median total dose was 60,000IU. N..
Dec 26 2020	Sistanizad et al., European Journal of Integrative Medicine, doi:10.1016/j.eujim.2020.101271	High dose vitamin D improves total serum antioxidant capacity and ICU outcome in critically ill patients - a randomized, double-blind clinical trial
	64% lower mortality (p=0.004). RCT of 30 ventilated ICU patients showing lower mortality with vitamin D treatment, RR 0.36, p = 0.004. Authors do not indicate why the patients were hospitalized or if any of the patients were COVID-19 patients. 300,000 IU intramuscular ..
Dec 22 2020	Cangiano et al., Aging, doi:10.18632/aging.202307	Mortality in an Italian nursing home during COVID-19 pandemic: correlation with gender, age, ADL, vitamin D supplementation, and limitations of the diagnostic tests
	70% lower mortality (p=0.04). 70% lower mortality with vitamin D supplementation. Analysis of 98 PCR+ nursing home residents in Italy, mean age 90, vitamin D supplementation RR 0.30, p = 0.04. The paper provides the p value for regression but not the effect size. Trea..
Dec 12 2020	Abdollahi et al., Journal of Medical Virology, doi:10.1002/jmv.26726	The Association Between the Level of Serum 25(OH) Vitamin D, Obesity, and underlying Diseases with the risk of Developing COVID-19 Infection: A case-control study of hospitalized patients in Tehran, Iran
	54% fewer cases (p=0.001). Case control study with 201 patients and 201 matched controls in Iran showing vitamin D deficiency associated with COVID-19.
Dec 11 2020	Ling et al., Nutrients, doi:10.3390/nu12123799	High-Dose Cholecalciferol Booster Therapy is Associated with a Reduced Risk of Mortality in Patients with COVID-19: A Cross-Sectional Multi-Centre Observational Study
	80% lower mortality (p=0.001). 80% lower mortality with cholecalciferol booster therapy. Retrospective 986 hospitalized patients in the UK finding that cholecalciferol booster therapy, regardless of baseline serum levels, was associated with a reduced risk of mortality..
Dec 10 2020	Rosenthal et al., JAMA Network Open, doi:10.1001/jamanetworkopen.2020.29058	Risk Factors Associated With In-Hospital Mortality in a US National Sample of Patients With COVID-19
	11% lower mortality (p=0.005). Retrospective database analysis of 64,781 hospitalized patients in the USA, showing lower mortality with vitamin C or vitamin D (authors do not distinguish between the two), and higher mortality with zinc and HCQ, statistically significan..
Dec 10 2020	VitaminDForAll, 12/2020	Over 100 Scientists, Doctors, & Leading Authorities Call For Increased Vitamin D Use To Combat COVID-19
	Over 100 scientists and doctors call for efforts to increase vitamin D levels. Recommendations include reaching 75 nmol/L serum levels, 2000-4000IU daily supplementation (in the absence of testing), and measurement and treatment in hospit..
Dec 9 2020	Vassiliou et al., Hellenic Journal of Cardiology, doi:10.1016/j.hjc.2020.11.011	Vitamin D deficiency correlates with a reduced number of natural killer cells in intensive care unit (ICU) and non-ICU patients with COVID-19 pneumonia
	Observational study of 29 ICU patients and 10 non-ICU patients showing vitamin D levels positively correlated with cytotoxic T cells, natural killer (NK) cells, NK-T cells, and regulatory T cells.
Dec 9 2020	Vassiliou et al., Nutrients, doi:10.3390/nu12123773	Low 25-Hydroxyvitamin D Levels on Admission to the Intensive Care Unit May Predispose COVID-19 Pneumonia Patients to a Higher 28-Day Mortality Risk: A Pilot Study on a Greek ICU Cohort
	91% lower mortality (p=0.04). Small prospective study of 30 ICU patients, showing higher mortality risk for low vitamin D levels. When divided into two groups at the median level, there was 5 of 15 deaths for the low vitamin D group compared to 0 of 15 in the high vit..
Dec 5 2020	Alguwaihes et al., Cardiovascular Diabetology, doi:10.1186/s12933-020-01184-4	Diabetes and Covid-19 among hospitalized patients in Saudi Arabia: a single-centre retrospective study
	86% lower mortality (p=0.007). Retrospective 439 diabetic hospitalized patients in Saudi Arabia showing lower mortality with vitamin D >12.5 nmol/L, adjusted hazard ratio aHR 0.14, p = 0.007.
Dec 4 2020	Katz et al., Nutrition, doi:10.1016/j.nut.2020.111106	Increased risk for Covid-19 in patients with Vitamin D deficiency
	78% fewer cases (p=0.001). Retrospective database analysis showing patients with vitamin D deficiency were 4.6 times more likely to be COVID-19 positive, p<0.001.
Nov 30 2020	Louca et al., BMJ Nutrition, Prevention & Health, doi:10.1136/bmjnph-2021-000250 (date from preprint)	Modest effects of dietary supplements during the COVID-19 pandemic: insights from 445 850 users of the COVID-19 Symptom Study app
	8% fewer cases (p=0.0007). Survey analysis of dietary supplements showing vitamin D usage associated with lower incidence of COVID-19. These results are for PCR+ cases only, they do not reflect potential benefits for reducing the severity of cases. A number of bias..
Nov 25 2020	De Smet et al., American Journal of Clinical Pathology, doi:10.1093/ajcp/aqaa252	Serum 25(OH)D Level on Hospital Admission Associated With COVID-19 Stage and Mortality
	70% lower mortality (p=0.02). Retrospective 186 hospitalized patients in Belgium showing that 59% of patients were vitamin D deficient, and that non-vitamin D deficient patients had significantly lower mortality risk, RR 0.26, p = 0.015.
Nov 19 2020	Jain et al., Nature, doi:10.1038/s41598-020-77093-z	Analysis of vitamin D level among asymptomatic and critically ill COVID-19 patients and its correlation with inflammatory markers
	85% lower mortality (p=0.001) and 95% lower ICU admission (p<0.0001). Prospective study of 91 asymptomatic and 63 ICU patients showing significantly higher vitamin D deficiency in the ICU patients (97% vs. 33%).
Nov 17 2020	Murai et al., JAMA, doi:10.1001/jama.2020.26848 (date from preprint)	Effect of a Single High Dose of Vitamin D3 on Hospital Length of Stay in Patients With Moderate to Severe COVID-19: A Randomized Clinical Trial
	49% higher mortality (p=0.43), 48% lower ventilation (p=0.09), 25% lower ICU admission (p=0.3), and 7% higher hospital discharge (p=0.63). Very late stage (mean 10 days from symptom onset, 90% on oxygen at baseline) vitamin D supplementation RCT not showing significant differences. Ethnicity was poorly matched between arms, and diabetes was 41% in the treatment arm vs. 29% i..
Nov 13 2020	Luo et al., The Journal of Nutrition, doi:10.1093/jn/nxaa332	Vitamin D Deficiency Is Associated with COVID-19 Incidence and Disease Severity in Chinese People
	63% lower progression (p=0.01). Retrospective 335 patients in China compared to 560 matched controls showing significanlty lower risk of severe COVID-19 with vitamin D sufficiency (≥30 nmol/L) OR 0.37, p = 0.014.
Nov 12 2020	Jungreis et al., medRxiv, doi:10.1101/2020.11.08.20222638	Mathematical analysis of Córdoba calcifediol trial suggests strong role for Vitamin D in reducing ICU admissions of hospitalized COVID-19 patients
	Analysis of Entrenas Castillo et al. [Entrenas Castillo] confirming efficacy of calcifediol treatment. Authors find that issues related to imperfect blinding and comorbidities can not explain the result found. See [compbio.mit.edu] for a ..
Nov 12 2020	Rastogi et al., Postgraduate Medical Journal, doi:10.1136/postgradmedj-2020-139065	Short term, high-dose vitamin D supplementation for COVID-19 disease: a randomised, placebo-controlled, study (SHADE study)
	53% improved viral clearance (p=0.02). 53% reduction in PCR+ with high-dose cholecalciferol supplementation. RCT with 16 treatment patients and 24 control patients. 25(OH)D levels at day 14 were 52 ng/ml vs. 15 ng/ml in the intervention and control group.
Nov 11 2020	Cereda et al., Nutrition, doi:10.1016/j.nut.2020.111055	Vitamin D supplementation and outcomes in coronavirus disease 2019 (COVID-19) patients from the outbreak area of Lombardy, Italy
	73% higher mortality (p=0.14) and 17% higher hospitalization (p=0.68). Retrospective 105 Parkinson's disease patients, 92 caregivers, and 127 hospital inpatients, showing higher, but not statistically significant mortality and hospitalization with treatment. Supplementation was defined as ≥25,000IU/month for..
Nov 9 2020	Walk et al., medRxiv, doi:10.1101/2020.11.07.20227512	Vitamin D - contrary to vitamin K - does not associate with clinical outcome in hospitalized COVID-19 patients
	no change in combined mortality/intubation (p=1). Small retrospective study of 135 patients not finding a significant difference in vitamin D status. Patients with good outcomes had a median of 45.0 nmol/L versus 37.7 nmol/L for bad outcomes, p = 0.85. Authors found that vitamin D suffic..
Nov 2 2020	Annweiler et al., Nutrients, doi:10.3390/nu12113377	Vitamin D Supplementation Associated to Better Survival in Hospitalized Frail Elderly COVID-19 Patients: The GERIA-COVID Quasi-Experimental Study
	93% lower mortality (p=0.02). Retrospective study finding that regular bolus vitamin D supplementation was associated with less severe COVID-19 and better survival in frail elderly. For those receiving regular supplementation: Adjusted mortality hazard ratio with supp..
Nov 1 2020	Cereda et al., Clinical Nutrition (Edinburgh, Scotland), doi:10.1016/j.clnu.2020.10.055	Vitamin D 25OH deficiency in COVID-19 patients admitted to a tertiary referral hospital
	120% higher mortality (p=0.04). Prospective cohort study of 129 adult hospitalized COVID-19 patients finding patients with vitamin D levels >20ng/mL had increased mortality after adjustment. This study does not account for the risk of having a serious enough case to be..
Oct 31 2020	Ohaegbulam et al., American Journal of Therapeutics, doi:10.1097/MJT.0000000000001222	Vitamin D Supplementation in COVID-19 Patients: A Clinical Case Series
	Small case study of 4 vitamin D deficient patients with 2 patients treated with cholecalciferol 1,000 IU daily and two patients treated with ergocalciferol 50,000 IU daily for 5 days (high dose), showing that patients receiving high dose ..
Oct 31 2020	Mercola et al., Nutrients 2020, 12:11, 3361, doi:10.3390/nu12113361	Evidence Regarding Vitamin D and Risk of COVID-19 and Its Severity
	Review of vitamin D and COVID-19 concluding that the evidence seems strong enough that people and physicians can use or recommend vitamin D supplements to prevent or treat COVID-19 in light of their safety and wide therapeutic window.
Oct 30 2020	Abrishami et al., European Journal of Nutrition, doi:10.1007/s00394-020-02411-0	Possible association of vitamin D status with lung involvement and outcome in patients with COVID-19: a retrospective study
	76% lower mortality (p=0.04). Retrospective 73 hospitalized patients showing the probability of death in patients with vitamin D deficiency (< 25ng/mL) was 34.6% compared with 6.4% in patients with sufficient vitamin D levels.
Oct 27 2020	Hernández et al., The Journal of Clinical Endocrinology & Metabolism, doi:10.1210/clinem/dgaa733	Vitamin D Status in Hospitalized Patients with SARS-CoV-2 Infection
	83% lower combined mortality/ICU admission (p=0.0001), 81% lower hospitalization (p=0.0001), 76% lower ventilation (p=0.13), and 79% lower ICU admission (p=0.05). Retrospective 216 COVID-19 patients and 197 population controls, showing vitamin D deficiency in 82.2% of COVID-19 cases and 47.2% of population-based controls (P < 0.0001). Authors note: "We did not find any relationship between vit..
Oct 26 2020	Tomasa-Irriguible et al., Metabolites, doi:10.3390/metabo11090565 (date from preprint)	Low Levels of Few Micronutrients May Impact COVID-19 Disease Progression: An Observational Study on the First Wave
	35% lower ventilation (p=0.21) and 17% lower ICU admission (p=0.58). Retrospective 120 hospitalized patients in Spain showing no significant differences for vitamin D deficiency.
Oct 24 2020	Sainz-Amo et al., Journal of Neurology, doi:10.1007/s00415-020-10272-0	COVID-19 in Parkinson’s disease: what holds the key?
	33% lower severe cases (p=0.45) and 44% fewer cases (p=0.23). Case control study with 39 COVID+ and 172 COVID- Parkinson's disease patients in Spain, showing positive and severe cases being less likely to use vitamin D supplementation compared to negative or mild/negative cases respectively. These d..
Oct 21 2020	Basha et al., Clinical Epidemiology and Global Health, doi:10.1016/j.cegh.2020.10.005	Is the shielding effect of cholecalciferol in SARS CoV-2 infection dependable? An evidence based unraveling
	Review of vitamin D for COVID-19, concluding that the available evidence is very suggestive of protective and preventive effect of vitamin D. Authors note that strict lockdown (longer time indoors and home quarantine) may increase the ris..
Oct 21 2020	Macaya et al., Nutr. Hosp., doi:10.20960/nh.03193	Interaction between age and vitamin D deficiency in severe COVID-19 infection
	55% lower severe cases (p=0.07). Retrospective 80 hospitalized patients in Spain showing higher risk of severe COVID-19 with vitamin D deficiency.
Oct 20 2020	Blanch-Rubió et al., Aging, doi:10.18632/aging.104117	Influence of anti-osteoporosis treatments on the incidence of COVID-19 in patients with non-inflammatory rheumatic conditions
	8% fewer cases (p=0.68). Retrospective 2,102 rheumatology patients in Spain showing no significant difference in cases with vitamin D supplementation. Details of vitamin D supplementation are not providied - other patients may have also independently taken vitami..
Oct 13 2020	Annweiler et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2020.105771	Vitamin D and survival in COVID-19 patients: A quasi-experimental study
	89% lower mortality (p=0.002). Vitamin D3 supplementation during or just before COVID-19 was associated with 68% lower mortality and less severe COVID-19 in frail elderly. Retrospective 66 French nursing home residents, mean age 87.7, 9 control patients, and 57 that re..
Oct 13 2020	Ye et al., Journal of the American College of Nutrition, doi:10.1080/07315724.2020.182600	Does Serum Vitamin D Level Affect COVID-19 Infection and Its Severity? A Case-Control Study
	93% lower hospitalization (p=0.03). Case control study in China comparing 62 patients with 80 healthy controls showing vitamin D deficiency is a risk factor for COVID-19, especially for severe/critical cases.
Oct 6 2020	Faniyi et al., medRxiv, doi:10.1101/2020.10.05.20206706	Vitamin D status and seroconversion for COVID-19 in UK healthcare workers who isolated for COVID-19 like symptoms during the 2020 pandemic
	29% lower seropositivity (p=0.003). Analysis of vitamin D status and anti-SARS-Cov-2 antibodies in UK healthcare workers finding that Vitamin D deficiency is a risk factor for COVID-19 seroconversion.
Oct 5 2020	Yılmaz et al., Pediatric Pulmonology, doi:10.1002/ppul.25106	Is vitamin D deficiency a risk factor for COVID-19 in children?
	73% lower severe cases (p=1). Retrospective 40 hospitalized pediatric COVID-19 patients and 45 healthy controls showing significantly lower vitamin D levels for COVID-19 patients (13.1 vs. 34.8µg/L), and that, within the hospitalized patients, there was more moderate ..
Oct 5 2020	Karahan et al., J. Nutr. Health Aging, doi:10.1007/s12603-020-1479-0	Impact of Serum 25(OH) Vitamin D Level on Mortality in Patients with COVID-19 in Turkey
	83% lower mortality (p<0.0001). Retrospective 149 COVID-19 patients, 69.1% with vitamin D deficiency, showing lower vitamin D levels associated with higher mortality.
Sep 30 2020	Kerget et al., Tuberk Toraks, doi:10.5578/tt.70027	Evaluation of the relationship of serum vitamin D levels in COVID-19 patients with clinical course and prognosis
	Prospective study of 88 hospitalized PCR+ COVID-19 patients and 20 asymptomatic PCR- medical personnel, showing lower vitamin D levels correlated with COVID-19 and with the development of ARDS and MAS.
Sep 29 2020	Pepkowitz et al., Research Square, doi:10.21203/rs.3.rs-83262/v1	Vitamin D Deficiency is Associated with Increased COVID-19 Severity: Prospective Screening of At-Risk Groups is Medically Indicated
	56% lower ICU admission (p=0.01). Retrospective 37 hospitalized patients in the USA, showing higher risk of ICU admission with vitamin D deficiency.
Sep 23 2020	Tomasa-Irriguible et al., Preprints, doi:10.20944/preprints202009.0555.v1	Up to 40% of COVID-19 Critically Ill Patients Have Vitamin D Deficiency
	Retrospective 35 ICU patients in Spain showing 71% of patients had vitamin D levels <20 ng/mL, and 40% <10 ng/mL.
Sep 17 2020	Kaufman et al., PLOS One, doi:10.1371/journal.pone.0239252	SARS-CoV-2 positivity rates associated with circulating 25-hydroxyvitamin D levels
	53% fewer cases (p=0.001). Analysis of 191,779 patients in the US finding COVID-19 positivity strongly and inversely associated with circulating 25(OH)D levels. The relationship persists across latitudes, races/ethnicities, gender, and age ranges. COVID-19 adjusted..
Sep 10 2020	Radujkovic et al., Nutrients 2020, 12:9, 2757, doi:10.3390/nu12092757	Vitamin D Deficiency and Outcome of COVID-19 Patients
	93% lower mortality (p=0.001) and 84% lower combined mortality/intubation (p=0.001). Observational study 185 patients in Germany shows an association between vitamin D status and severity and mortality. Adjusted hazard ratio of vitamin D sufficiency for combined mechanical ventilation and death was HR 0.16, p < 0.001, and..
Sep 8 2020	Galmés et al., Nutrients, doi:10.3390/nu12092738	Current State of Evidence: Influence of Nutritional and Nutrigenetic Factors on Immunity in the COVID-19 Pandemic Framework
	Ecological study of European countries analyzing 10 vitamins and minerals endorsed by the European Food Safety Authority as having sufficient evidence for a causal relationship between intake and optimal immune system function: vitamins D..
Sep 3 2020	Meltzer et al., JAMA network open, 3:9, doi:10.1001/jamanetworkopen.2020.19722	Association of Vitamin D Status and Other Clinical Characteristics With COVID-19 Test Results
	44% fewer cases (p=0.02). Retrospective 489 patients showing 44% lower risk for COVID-19 with vitamin D sufficiency, relative risk RR = 0.56, p = 0.02.
Sep 2 2020	Daneshkhah et al., Aging Clinical and Experimental Research, doi:10.1007/s40520-020-01677-y	Evidence for possible association of vitamin D status with cytokine storm and unregulated inflammation in COVID-19 patients
	Retrospective ecological study of vitamin D levels and COVID-19 mortality in 9 countries suggesting a possible association between lower population vitamin D levels and higher COVID-19 mortality. Authors use national vitamin D data and pe..
Aug 29 2020	Entrenas Castillo et al., Journal of Steroid Biochemistry and Molecular Biology, 203, October 2020, doi:10.1016/j.jsbmb.2020.105751	Effect of calcifediol treatment and best available therapy versus best available therapy on intensive care unit admission and mortality among patients hospitalized for COVID-19: A pilot randomized clinical study
	85% lower mortality (p=0.11) and 94% lower ICU admission (p=0.008). RCT on calcifediol (25-hydroxyvitamin D) treatment for hospitalized COVID-19 patients showing significantly reduced intensive care unit admissions. All patients received standard care including HCQ+AZ. For additional analysis see Jungreis..
Aug 28 2020	Mardani et al., Virus Research, doi:10.1016/j.virusres.2020.198148	Association of vitamin D with the modulation of the disease severity in COVID-19
	Prospective study of 123 outpatients in Iran, showing mortality associated with significantly lower vitamin D levels. IR.SBMU.RETECH.REC.1399.131.
Aug 27 2020	Baktash et al., Postgraduate Medical Journal, doi:10.1136/postgradmedj-2020-138712	Vitamin D status and outcomes for hospitalised older patients with COVID-19
	29% lower mortality (p=0.5). Prospective study of 105 hospitalized patients, showing lower vitamin D levels in the COVID-19 positive group (27.0 nmol/L vs 52.0 nmol/L, p=0.0008), and non-statistically significant higher mortality with vitamin D deficiency.
Aug 26 2020	Xu et al., Journal of Translational Medicine, doi:10.1186/s12967-020-02488-5	The importance of vitamin d metabolism as a potential prophylactic, immunoregulatory and neuroprotective treatment for COVID-19
	Review of vitamin D for the prevention and treatment of COVID-19, focusing on preventing SARS-CoV-2 infection, acting as an immunosuppressant inhibiting cytokine release syndrome, and preventing loss of neural sensation by stimulating exp..
Aug 26 2020	Afshar et al., Journal of Contemporary Medical Sciences, doi:10.22317/jcms.v6i4.822	Suggested role of Vitamin D supplementation in COVID-19 severity
	Brief report noting that there was a dramatic and complete resolution of ICU admissions after adding routine vitamin D supplementation to standard of care.
Aug 26 2020	Hastie et al., Diabetes and Metabolic Syndrome: Clinical Research and Reviews, 14:4, 561–565, doi:10.1016/j.dsx.2020.04.050	Vitamin D concentrations and COVID-19 infection in UK Biobank
	17% lower mortality (p=0.31) and 9% lower hospitalization (p=0.4). Database analysis of 341,484 patients in the UK with 656 hospitalized confirmed COVID-19 patients and 203 deaths, not showing a statistically significant difference after adjustment. Since adjustment factors may be correlated with vitamin..
Aug 15 2020	Espitia-Hernandez et al., Biomedical Research, 31:5	Effects of Ivermectin-azithromycin-cholecalciferol combined therapy on COVID-19 infected patients: A proof of concept study
	70% faster recovery (p=0.0001) and 97% improved viral clearance (p<0.0001). Small study with 28 patients treated with ivermectin + AZ + cholecalciferol and 7 control patients. All treated patients were PCR- at day 10 while all control patients remained PCR+. The mean duration of symptoms was 3 days in the treatme..
Aug 11 2020	Im et al., International Journal of Infectious Diseases, doi:10.1016/j.ijid.2020.08.018	Nutritional status of patients with COVID-19
	73% fewer cases (p=0.0003). Analysis of 50 hospitalized COVID-19 patients in South Korea showing that 76% of patients were vitamin D deficient. Comparison with 150 matched controls showed a higher probability of cases with vitamin D deficiency.
Aug 9 2020	Carpagnano et al., J. Endocrinol. Invest., 2020, Aug 9, 1-7, doi:10.1007/s40618-020-01370-x	Vitamin D deficiency as a predictor of poor prognosis in patients with acute respiratory failure due to COVID-19
	71% lower mortality (p=0.05). Retrospective study 42 patients with acute respiratory failure, 81% with low vitamin D levels. After 10 days, patients with severe vitamin D deficiency had a 50% probability of dying, while those with vitamin D ≥ 10 ng/mL had a 5% mortali..
Aug 7 2020	Alexander et al., Nutrients, doi:10.3390/nu12082358	Early Nutritional Interventions with Zinc, Selenium and Vitamin D for Raising Anti-Viral Resistance Against Progressive COVID-19
	Review exploring the potential of early nutritional intervention with zinc, selenium and vitamin D to prevent progression of COVID-19, based on the importance of these micronutrients for anti-viral resistance and reduced inflammation. Aut..
Jul 31 2020	Anjum et al., Pakistan J. Med. Heal. Sci., 14:3	Examine the association between severe vitamin D deficiency and mortality in patients with Covid-19
	62% lower mortality (p=0.02). Prospective study of 140 COVID-19 patients in Pakistan, showing significantly higher mortality with vitamin D deficiency.
Jul 23 2020	Merzon et al., The FEBS Journal, doi:10.1111/febs.15495	Low plasma 25(OH) vitamin D level is associated with increased risk of COVID-19 infection: an Israeli population-based study
	46% lower hospitalization (p=0.06) and 28% fewer cases (p=0.001). Analysis of 7,807 patients finding that low vitamin D levels are correlated with increased risk of cases and hospitalization. Adjusted odds ratio OR for sufficient vitamin D level for cases 0.69, p < 0.001, and for hospitalization 0.51, p..
Jul 23 2020	Lansiaux et al., Spat. Spatiotemporal Epidemiol, doi:10.1016/j.sste.2020.100362	Covid-19 and vit-d: Disease mortality negatively correlates with sunlight exposure
	Analysis of COVID-19 mortality and sunlight exposure in continental metropolitan France, showing that average annual sunlight hours were significantly correlated with COVID-19 mortality, with a Pearson coefficient of -0.636. Also see the ..
Jul 20 2020	Krishnan et al., Journal of Clinical Anesthesia, doi:10.1016/j.jclinane.2020.110005	Clinical comorbidities, characteristics, and outcomes of mechanically ventilated patients in the State of Michigan with SARS-CoV-2 pneumonia
	19% lower mortality (p=0.42). Retrospective 152 mechanically ventilated patients in the USA showing unadjusted lower mortality with vitamin C, vitamin D, HCQ, and zinc treatment, statistically significant only for vitamin C.
Jul 17 2020	Jolliffe et al., medRxiv, doi:10.1101/2020.07.14.20152728	Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of aggregate data from randomised controlled trials
	Meta analysis of 40 RCTs showing that vitamin D supplementation is safe and reduced risk of acute respiratory infections, odds ratio OR 0.89 [0.81-0.98].
Jul 4 2020	Chang et al., medRxiv, doi:10.1101/2020.07.03.20145581	Prior diagnoses and medications as risk factors for COVID-19 in a Los Angeles Health System
	43% fewer cases (p<0.0001). Retrospective 26,602 individuals tested for SARS-CoV-2 showing increased COVID-19 susceptibility with vitamin D deficiency.
Jun 30 2020	Hamza et al., Pakistan Journal of Medical & Health Sciences	Role of Vitamin D in Pathogenesis and Severity of Coronavirus Disease 2019 (COVID-19) Infection
	Prospective study of 168 patients in Pakistan reporting an association between vitamin D deficiency and symptomatic cases. Details of the association are not provided.
Jun 30 2020	Faul et al., Irish Medical Journal, 113:5, 84	Vitamin D Deficiency and ARDS after SARS-CoV-2 Infection
	69% lower ventilation (p=0.03). Analysis of 33 hospitalized COVID-19 patients with respiratory failure requiring FiO₂ greater than 0.4. Intubation hazard ratio for vitamin D sufficiency HR 0.31, p = 0.03.
Jun 30 2020	Panagiotou et al., medRxiv, doi:10.1101/2020.06.21.20136903	Low serum 25-hydroxyvitamin D (25[OH]D) levels in patients hospitalised with COVID-19 are associated with greater disease severity: results of a local audit of practice
	52% lower ICU admission (p=0.02). Retrospective analysis 134 hospitalized patients. 19% of ICU patients had 25(OH)D levels > 50 nmol/L vs. 39.1% of non-ICU patients, p=0.02
Jun 27 2020	Mendy et al., medRxiv, doi:10.1101/2020.06.25.20137323	Factors Associated with Hospitalization and Disease Severity in a Racially and Ethnically Diverse Population of COVID-19 Patients
	7% lower mortality (p=0.89), 17% lower combined mortality/ICU admission (p=0.001), 55% lower ICU admission (p=0.008), and 15% lower hospitalization (p=0.001). Retrospective 689 patients showing vitamin D deficiency associated with hospitalization and disease severity.
Jun 26 2020	Whittemore et al., American Journal of Infection Control, doi:10.1016/j.ajic.2020.06.193	COVID-19 fatalities, latitude, sunlight, and vitamin D
	Analysis of 88 countries, showing a significant correlation between death rates and latitude, suggesting that sunlight exposure and vitamin D levels influence mortality.
Jun 24 2020	Andrade et al., SciELO preprints, doi:10.1590/SciELOPreprints.839	Vitamin A and D deficiencies in the prognosis of respiratory tract infections: A systematic review with perspectives for COVID-19 and a critical analysis on supplementation
	Systematic review showing deficiencies of vitamins A and D negatively affecting the prognosis of respiratory tract infections.
Jun 22 2020	Mok et al., bioRxiv, doi:10.1101/2020.06.21.162396	Calcitriol, the active form of vitamin D, is a promising candidate for COVID-19 prophylaxis
	In vitro study showing that the active form of Vitamin D, calcitriol, exhibits significant potent activity against SARS-CoV-2.
Jun 19 2020	Raisi-Estabragh et al., J. Public Health, doi:10.1093/pubmed/fdaa095	Greater risk of severe COVID-19 in Black, Asian and Minority Ethnic populations is not explained by cardiometabolic, socioeconomic or behavioural factors, or by 25(OH)-vitamin D status: study of 1326 cases from the UK Biobank
	UK Biobank retrospective not finding a significant association between vitamin D levels and the risk of PCR+ after adjustment. Since adjustment factors may be correlated with vitamin D deficiency, the extent of any causal contribution of ..
Jun 14 2020	Rhodes et al., BMJ Nutr. Prev. Health, doi:10.1136/bmjnph-2020-000110	COVID-19 mortality increases with northerly latitude after adjustment for age suggesting a link with ultraviolet and vitamin D
	Analysis of COVID-19 mortality and latitude as of May 18, 2020, showing that latitude was significantly associated with mortality (p=0.031), with an estimated 4.4% [0.4%-8.5%] increase in mortality for each 1° further north.
Jun 13 2020	Davies et al., medRxiv, doi:10.1101/2020.05.01.20087965	Evidence Supports a Causal Role for Vitamin D Status in Global COVID-19 Outcomes
	Causal inference analysis of COVID-19 severity and latitude concluding that vitamin D status plays a key role in COVID-19 outcome.
Jun 10 2020	Tan et al., Nutrition, doi:10.1016/j.nut.2020.111017 (date from preprint)	Cohort study to evaluate the effect of combination Vitamin D, Magnesium and Vitamin B12 (DMB) on progression to severe outcome in older COVID-19 patients
	80% lower need for oxygen therapy (p=0.04) and 81% lower ICU admission (p=0.07). Observational study of 43 patients ≥50 years old, with 17 patients receiving vitamin D, magnesium, and vitamin B12 (DMB); and 26 control patients, showing a significantly lower need for oxygen therapy and ICU admission with treatment. DMB..
Jun 2 2020	Li et al., Research Square, doi:10.21203/rs.3.rs-32499/v1	Sunlight and vitamin D in the prevention of coronavirus disease (COVID-19) infection and mortality in the United States
	Analysis of COVID-19 cases in the USA reporting a potential relationship between latitude and the number of COVID-19 cases (p = 0.08) and deaths (p=0.06). Authors note that sunlight and vitamin D may reduce risk for COVID-19 cases and dea..
May 27 2020	Skutsch et al., medRxiv, doi:10.1101/2020.05.25.20112805	The association of UV with rates of COVID-19 transmission and deaths in Mexico: the possible mediating role of vitamin D
	Analysis of UV, temperature, humidity and COVID-19 in 45 Mexican cities, showing that UV was negatively correlated with rates of transmission (statistically significant) and mortality (not statistically significant).
May 14 2020	Chodick et al., Journal of Travel Medicine, doi:10.1093/jtm/taaa069	Angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers are not associated with increased risk of SARS-CoV-2 infection
	Retrospective 14,520 patients in Israel, 1,317 testing positive, showing no significant difference in vitamin D levels (23.6ng/mL and 24.1ng/mL for positive and negative cases respectively).
May 9 2020	D'Avolio et al., Nutrients, 12:5, 1–7, doi:10.3390/nu12051359	25-hydroxyvitamin D concentrations are lower in patients with positive PCR for SARS-CoV-2
	Retrospective 107 patients in Switzerland showing lower vitamin D levels (11.1 ng/mL) in PCR positive patients compared with negative patients (24.6 ng/mL), p = 0.004.
Apr 30 2020	Reyes Pérez et al., Revista de Sanidad Militar, doi:10.35366/93773	Deficiency of vitamin D is a risk factor of mortality in patients with COVID-19
	62% lower mortality (p=0.006). Retrospective 172 hospitalized COVID-19 patients in Mexico, reporting a very high prevalence of vitamin D deficiency, and significantly higher mortality with low vitamin D levels in unadjusted results.
Apr 28 2020	Marik et al., Med Drug Discov., doi:10.1016/j.medidd.2020.100041	Does vitamin D status impact mortality from SARS-CoV-2 infection?
	Analysis of case fatality rates showing that the CFR was significantly greater for Northern states (>40° latitude) compared to Southern States (6.0% vs. 3.5%, p < 0.001), although there were some exceptions with individual states.
Apr 28 2020	Lau et al., medRxiv, doi:10.1101/2020.04.24.20075838	Vitamin D Insufficiency is Prevalent in Severe COVID-19
	45% lower ICU admission (p=0.29). Analysis of 20 hospitalized COVID-19 patients, 13 requiring ICU admission. 84.6% of the ICU patients had low vitamin D levels versus 57.1% of the non-ICU patients.
Apr 2 2020	Grant et al., Nutrients, 12:4, 988, doi:10.3390/nu12040988	Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths
	Review of the evidence that vitamin D supplementation could reduce COVID-19 risk.
Jan 4 2019	McCullough et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2018.12.010	Daily oral dosing of vitamin D3 using 5000 TO 50,000 international units a day in long-term hospitalized patients: Insights from a seven year experience
	Report on the long-term use of vitamin D in hospitalized patients with daily dosing from 5,000 to 50,000IU over 7 years. There were no cases of hypercalcemia or any adverse events related to vitamin D supplementation. Authors conclude tha..
Jan 6 2018	Carlberg et al., The Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2018.01.002	In vivo response of the human epigenome to vitamin D: A Proof-of-principle study
	Epigenome-wide chromatin accessibility study before and after vitamin D supplementation (calcitriol), showing significant changes at hundreds of sites within the epigenome of human leukocytes (part of the immune system).
Feb 15 2017	Martineau et al., BMJ 2017, 356, doi:10.1136/bmj.i6583	Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data
	7% fewer cases (p=0.003). Meta analysis of 25 RCTs showing vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most be..
Nov 16 2016	Ginde et al., Journal of the American Geriatrics Society, doi:10.1111/jgs.14679	High‐Dose Monthly Vitamin D for Prevention of Acute Respiratory Infection in Older Long‐Term Care Residents: A Randomized Clinical Trial
	Non-COVID-19 RCT with 107 older long-term care residents showing significantly lower incidence of acute respiratory tract infections but higher incidence of falls with monthly high-dose (100,000 IU) vitamin D supplementation compared to s..
Feb 25 2010	EFSA, EFSA Journal, doi:10.2903/j.efsa.2010.1468	Scientific Opinion on the substantiation of health claims related to vitamin D and normal function of the immune system and inflammatory response (ID 154, 159), maintenance of normal muscle function (ID 155) and maintenance of normal cardiovascular function (ID 159) pursuant to Article 13(1) of Regulation (E
	European Food Safety Administration review concluding that there is a causal relationship between the intake of vitamin D and immune system function.
May 31 2015	EFSA, EFSA Journal, doi:10.2903/j.efsa.2015.4096	Scientific Opinion on the substantiation of a health claim related to vitamin D and contribution to the normal function of the immune system pursuant to Article 14 of Regulation (EC) No 1924/2006
	European Food Safety Administration review concluding that there is a causal relationship between the intake of vitamin D and immune system function.
Feb 1 2014	Quraishi et al., JAMA Surgery, doi:10.1001/jamasurg.2013.3176	Association Between Preoperative 25-Hydroxyvitamin D Level and Hospital-Acquired Infections Following Roux-en-Y Gastric Bypass Surgery
	Retrospective 770 gastric bypass surgery patients showing a strong relationship between pre-operative vitamin D levels and the risk of hospital acquired infections.
Oct 1 2014	Palacios et al., J Steroid Biochem Mol Biol., 2014, 144PA, 138–145, doi:10.1016/j.jsbmb.2013.11.003	Is vitamin D deficiency a major global public health problem?
	Review showing vitamin D deficiency is common worldwide in all age groups.
Jun 19 2013	Bergman et al., PLoS ONE, 2013, 8:6, doi:10.1371/journal.pone.0065835	Vitamin D and Respiratory Tract Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
	Meta analysis of 11 placebo-controlled studies of 5660 patients. Vitamin D showed a protective effect against RTI (OR 0.64 [0.49-0.84]). The protective effect was larger in studies using once-daily dosing compared to bolus doses (OR = 0.5..
Nov 1 2012	Mitchell et al., Endocr. Pract., 2012, 18:6, 914–923, doi:10.4158/EP12072.OR	Prevalence and predictors of vitamin D deficiency in healthy adults
	Study of 634 healthy volunteers showing 64% had 25(OH)D ≤ 30 ng/mL. Gender, ethnicity, and multivitamin use were significantly associated with 25(OH)D levels.
Mar 10 2010	Urashima et al., Am. J. Clin. Nutr. 2010, 91:5, 1255-60, doi:10.3945/ajcn.2009.29094	Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren
	RCT for vitamin D supplementation and seasonal influenza A in schoolchildren, showing 10.8% incidence in children in the vitamin D3 group compared with 18.6% in the placebo group, relative risk RR 0.58 [0.34-0.99], p = 0.04. The reduction..
Jul 31 2009	Grant et al., Dermato-Endocrinology, doi:10.4161/derm.1.4.9063	The possible roles of solar ultraviolet-B radiation and vitamin D in reducing case-fatality rates from the 1918–1919 influenza pandemic in the United States
	Analysis of the 1918-1919 influenza pandemic for 12 US states, showing estimated UVB dose correlated with case fatality rates (p = 0.009) and with pneumonia as a complication of influenza (p = 0.005).
Sep 7 2006	Cannell et al., Epidemiol Infect., 2006, 134:6. 1129-40, doi:10.1017/S0950268806007175	Epidemic influenza and vitamin D
	Review article on the mechanisms of action and seasonality of vitamin D levels, concluding that varying vitamin D levels may be the reason for the seasonality of epidemic influenza.

For search methods, inclusion criteria, effect extraction criteria (more serious outcomes have priority), PRISMA answers, and statistical methods see methods. Studies with preprints and journal versions are listed under the earlier preprint date.

References

Covid Analysis, Vitamin D reduces COVID-19 risk: real-time meta-analysis of 370 studies (138 treatment studies and 232 sufficiency studies) (Version 340), c19early.org/dmeta.htmlc19early.org.

vitamindforall.org, vitamindforall.org/letter.html.