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Summary of COVID-19 probiotics studies

Studies   Meta Analysis   Hide extended summaries

73 patient probiotics early treatment RCT: 60% improved recovery (p=0.02) and 68% lower PASC (p=0.008).
RCT 73 outpatients with mild COVID-19 showing improved recovery and increased RBD/spike antibody response with 28 days of a multi-strain probiotic (Bifidobacterium (B.) lactis BI040, B. longum BL020, Lactobacillus (L) rhamnosus LR110, L. casei LC130, L. acidophilus LA120, 5 billion CFU total).

Jan 2024, BMC Nutrition,,

128 patient probiotics prophylaxis RCT: 98% fewer cases (p<0.0001).
Interim report on an RCT for prophylactic treatment with S. salivarius K12, showing significantly lower cases with treatment. Only patients with symptoms or known positive contacts were tested. Trial identification/registration details are not provided.

Mar 2021, Minerva Medica,,

80 patient probiotics late treatment RCT: 86% lower ICU admission (p=0.24) and 26% shorter hospitalization (p=0.52).
RCT 80 COVID-19 interstitial pneumonia patients in Italy, 40 treated with probiotics, showing significantly reduced gut inflammatory markers with treatment, and lower ICU admission and mortality, without statistical significance. Bifidobacterium lactis LA 304, lactobacillus salivarius LA 302, and lactobacillus acidophilus LA 201 bid for 10 days.

Jun 2022, J. Clinical Medicine,,

350 patient probiotics early treatment RCT: 50% fewer combined hospitalization/ER visits (p=0.13) and 20% faster recovery (p=0.1).
RCT 350 COVID+ outpatients in the USA, 174 treated with prebiotic KB109 (a microbiome metabolic therapy candidate), showing lower combined hospitalization, ER, and urgent care visits with treatment. NCT04414124.

Mar 2021, medRxiv,,

182 patient probiotics prophylaxis RCT: 33% fewer moderate/severe cases (p=0.15), 38% fewer symptomatic cases (p=0.02), 27% faster recovery (p=0.37), and 43% fewer cases (p=0.17).
RCT 182 COVID-19 exposed patients, 91 treated with daily probiotic Lactobacillus rhamnosus GG starting a median of 3 days from exposure, showing lower symptomatic COVID-19 with treatment. There were no hospitalizations or deaths.

Jan 2022, medRxiv,,

293 patient probiotics early treatment RCT: 35% improved recovery (p<0.0001).
RCT 293 outpatients in Mexico, 147 treated with a probiotic composed of three L. plantarum strains (KABP022, KABP023 and KABP033) and one P. acidilacti strain (KABP021), showing improved recovery with treatment. There were no hospitalizations or deaths.

May 2021, Gut Microbes,,

200 patient probiotics late treatment study: 64% lower mortality (p=0.003) and 15% lower ICU admission (p=0.6).
Retrospective 200 severe condition hospitalized patients in Italy, 88 treated with probiotic Sivomixx, showing lower mortality with treatment.

Jan 2021, Frontiers in Medicine,,

287 patient probiotics prophylaxis study: 78% fewer cases (p=0.007).
Retrospective study of 287 nursery school children in Italy, 186 treated with S. salivarius K12 probiotic. The probiotic group had significantly lower rates of COVID-19, bronchitis, sinusitis, and laryngitis as well as lower antibiotic use. The study was registered retrospectively and details of COVID-19 diagnosis are not provided. Parents that administer the treatment may also use other treatments or take other actions that reduce risk for their children.

Sep 2023, Minerva Medica,,

70 patient probiotics late treatment study: 87% lower mortality (p=0.14) and 88% lower progression (p=0.01).
Retrospective 70 hospitalized patients in Italy, 28 treated with probiotic Sivomixx, showing lower risk of respiratory failure and faster recovery with treatment.

Jul 2020, Frontiers in Medicine,,

35 patient probiotics late treatment study: 78% lower mortality (p=0.28) and 78% improvement (p=0.0001).
Retrospective COVID-19 patients requiring CPAP, 21 treated with SLAB51 probiotics and 15 control patients, showing improved outcomes with treatment, despite significantly lower blood oxygenation at baseline in the treatment group.

Jul 2022, Biomedicines,,

120 patient probiotics prophylaxis study: 40% improved recovery (p=0.008).
Retrospective 60 patients in Romania taking probiotics and 60 matched controls, showing faster symptom resolution with the use of probiotics. Spore-based probiotic containing five strains of Bacillus.

Jan 2023, Nutrients,,

60 patient probiotics prophylaxis RCT: 73% fewer symptomatic cases (p=0.35) and 85% fewer cases (p=0.24).
Small RCT 60 healthcare workers in Iran, showing lower cases with treatment but without statistical significance. Once daily oral synbiotic capsule (Lactocare®) containing 1 billion CFU L. (Lactobacillus) casei, L. rhamnosus, Streptococcus thermophilus, Bifidobacterium breve, L. acidophilus, Bifidobacterium infantis, L. bulgaricus, and Fructooligosacharide.

May 2021, Open J. Nursing,,

300 patient probiotics late treatment study: 14% shorter hospitalization (p=0.009), 14% faster recovery (p=0.02), and 17% faster viral clearance (p=0.001).
Retrospective 375 patients in China, 179 treated with probiotics (Bifidobacterium, Lactobacillus, and Enterococcus), showing improved clinical outcomes with treatment.

Aug 2021, Therapeutic Advances in Gastroenterology ,,

827 patient probiotics prophylaxis RCT: 33% fewer cases (p=1).
RCT 827 children aged 1-6 years in daycare in Finland analyzing the effectiveness of daily Streptococcus salivarius K12 oral probiotic use for 6 months in preventing acute otitis media (AOM). The probiotic group did not have a significantly lower rate of AOM requiring antibiotics compared to placebo. A secondary outcome shows no significant difference in COVID-19, with only 2 and 3 cases in the treatment and placebo groups.

Nov 2023, JAMA Network Open,,

39 patient probiotics early treatment RCT: 33% improved recovery (p=0.08).
RCT with 24 probiotics and 15 control patients in Spain, showing lower overall symptoms and lower digestive symptoms with treatment. Kluyveromyces marxianus B0399 plus lactobacillus rhamnosus CECT 30579.

Aug 2022, Medicine in Microecology,,

55 patient probiotics late treatment study: 67% improvement (p=0.06).
Pilot study of probiotic SIM01 with 25 consecutive COVID-19 patients in Hong Kong and 30 control patients treated by a different team during the same time period, showing improved antibody formation, reduced viral load and pro-inflammatory responses, and improvements for gut dysbiosis. SIM01 contains bifidobacteria strains, galactooligosaccharides, xylooligosaccharide, and resistant dextrin (derived from metagenomic databases of COVID-19 patients and healthy patients).

Mar 2022, J. Gastroenterology and Hepatology,,

69 patient probiotics late treatment study: 82% lower ICU admission (p=0.15).
Prospective analysis of 69 severe COVID-19 patients requiring non-invasive oxygen therapy, 40 treated with probiotic formulation SLAB51, showing lower oxygen requirements and higher blood levels of pO2, O2Hb and SaO2 with treatment. Authors suggest that enzymes in SLAB51 could reduce oxygen requirements in intestinal cells, resulting in more oxygen available for other organs.

Aug 2021, Nutrients,,

60 patient probiotics late treatment RCT: 11% faster recovery (p=0.19) and 11% shorter hospitalization (p=0.18).
Small RCT 60 patients in India, 30 treated with ImmunoSEB and ProbioSEB CSC3, showing faster recovery with treatment. CTRI/2020/09/027685, CTRI/2020/08/027168.

Feb 2021, Advances in Clinical Toxicology,,

100 patient probiotics early treatment RCT: 80% lower hospitalization (p=0.2) and 18% improved recovery (p=0.42).
RCT 150 patients in Egypt showing no significant difference in outcomes with probiotic lactobacillus acidophilus, although hospitalization was 2% versus 10% for control. SOC included vitamin C, D, and zinc.

Jun 2023, Research Square,,

50 patient probiotics late treatment RCT: 62% lower mortality (p=0.17) and no change in ICU admission (p=1).
RCT 50 hospitalized patients in Pakistan, 25 treated with S. salivarius K12, showing lower mortality with treatment, without statistical significance. There were more patients with higher oxygen requirements at baseline in the control group - 18 vs. 6 with O2 ≥ 8 L/min.

Sep 2022, Microorganisms,,

255 patient probiotics prophylaxis RCT: 9% fewer cases (p=0.92).
Prophylaxis RCT with 127 probiotics and 128 control healthcare workers in Spain, showing no significant difference in cases. There were only 4 cases. Severity information by arm is not provided. L. coryniformis K8 CECT 5711. Treatment may help sustain the immune response to vaccination - in the subgroup of subjects for whom more than 81 days had passed since they received the first dose, IgG levels were significantly higher in the treatment group. Patients that started probiotic consumption before the first vaccine dose also reported significantly fewer side effects.

Aug 2022, Frontiers in Nutrition,,

372,720 patient probiotics prophylaxis study: 8% fewer cases (p=0.03).
Survey analysis of dietary supplements showing probiotic 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 biases could affect the results, for example users of the app may not be representative of the general population, and people experiencing symptoms may be more likely to install and use the app.

Nov 2020, BMJ Nutrition, Prevention & Health,,

15,227 patient probiotics prophylaxis study: 30% fewer cases (p=0.11).
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. Statistical significance was not reached for any of these. Except for vitamin D, the results for treatments we follow were only adjusted for age, sex, duration of participation, and test frequency. NCT04330599. COVIDENCE UK.

Mar 2021, Thorax,,

200 patient probiotics late treatment RCT: 2% higher mortality (p=1), 18% lower ventilation (p=1), 27% lower ICU admission (p=0.77), and 5% faster recovery (p=0.47).
RCT 200 patients, 99 treated with a probiotic (Lacticaseibacillus rhamnosus PDV 1705, Bifidobacterium bifidum PDV 0903, Bifidobacterium longum subsp. infantis PDV 1911, and Bifidobacterium longum subsp. longum PDV 2301). There was no significant difference in mortality or recovery time, however benefits were seen for diarrhea. NCT04854941.

Oct 2021, Probiotics Antimicrob Proteins,,

30 patient probiotics early treatment study: 29% faster viral clearance (p=0.22).
Small case control analysis with 15 probiotics patients and 15 contol patients, showing no significant differences. PCR tests were only done weekly. Dosage is unknown. 115/LOE/301.4.2/IX/2020.

Jun 2021, Indian J. Forensic Medicine & Toxicology,,

311 patient probiotics late treatment study: 12% lower hospital discharge (p=0.68) and 35% slower viral clearance (p=0.001).
Retrospective 311 severe condition hospitalized patients in China, 123 treated with probiotics, showing slower viral clearance and recovery with treatment. Authors note that probiotics were able to moderate immunity and decrease the incidence of secondary infections.

Mar 2021, Int. Immunopharmacology,,
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