Abstract: Original Investigation | Infectious Diseases Association of Vitamin D Status and Other Clinical Characteristics With COVID-19 Test Results David O. Meltzer, MD, PhD; Thomas J. Best, PhD; Hui Zhang, PhD; Tamara Vokes, MD; Vineet Arora, MD, MPP; Julian Solway, MD Abstract Key Points IMPORTANCE Vitamin D treatment has been found to decrease the incidence of viral respiratory tract infection, especially in patients with vitamin D deficiency. Whether vitamin D is associated with coronavirus disease 2019 (COVID-19) incidence is unknown. Question Is vitamin D status, reflecting vitamin D levels and treatment, associated with test results for coronavirus disease 2019 (COVID-19)? OBJECTIVE To examine whether the last vitamin D status before COVID-19 testing is associated with Findings In this cohort study of 489 COVID-19 test results. patients who had a vitamin D level measured in the year before COVID-19 DESIGN, SETTING, AND PARTICIPANTS This retrospective cohort study at an urban academic testing, the relative risk of testing medical center included patients with a 25-hydroxycholecalciferol or 1,25-dihydroxycholecalciferol positive for COVID-19 was 1.77 times level measured within 1 year before being tested for COVID-19 from March 3 to April 10, 2020. greater for patients with likely deficient vitamin D status compared with patients EXPOSURES Vitamin D deficiency was defined by the last measurement of with likely sufficient vitamin D status, a 25-hydroxycholecalciferol less than 20 ng/mL or 1,25-dihydroxycholecalciferol less than 18 pg/mL difference that was statistically before COVID-19 testing. Treatment changes were defined by changes in vitamin D type and dose significant. between the date of the last vitamin D level measurement and the date of COVID-19 testing. Vitamin D deficiency and treatment changes were combined to categorize the most recent vitamin D status before COVID-19 testing as likely deficient (last level deficient and treatment not increased), likely sufficient (last level not deficient and treatment not decreased), and 2 groups with uncertain deficiency (last level deficient and treatment increased, and last level not deficient and treatment decreased). Meaning These findings appear to support a role of vitamin D status in COVID-19 risk; randomized clinical trials are needed to determine whether broad population interventions and interventions among groups at increased risk of vitamin D deficiency MAIN OUTCOMES AND MEASURES The outcome was a positive COVID-19 polymerase chain reaction test result. Multivariable analysis tested whether vitamin D status before COVID-19 testing and COVID-19 could reduce COVID-19 incidence. was associated with testing positive for COVID-19, controlling for demographic and comorbidity indicators. + Supplemental content RESULTS A total of 489 patients (mean [SD] age, 49.2 [18.4] years; 366 [75%] women; and 331 [68%] race other than White) had a vitamin D level measured in the year before COVID-19 testing. Author affiliations and article information are listed at the end of this article. Vitamin D status before COVID-19 testing was categorized as likely deficient for 124 participants (25%), likely sufficient for 287 (59%), and uncertain for 78 (16%). Overall, 71 participants (15%) tested positive for COVID-19. In multivariate analysis, testing positive for COVID-19 was associated with increasing age up to age 50 years (relative risk, 1.06; 95% CI, 1.01-1.09; P = .02);..