Assessment of the Association of Vitamin D Level With SARS-CoV-2 Seropositivity Among Working-Age Adults
JAMA Network Open, doi:10.1001/jamanetworkopen.2021.11634
IMPORTANCE Low vitamin D levels have been reported to be associated with increased risk of SARS-CoV-2 infection. Independent, well-powered studies could further our understanding of this association.
OBJECTIVE To examine whether low levels of vitamin D are associated with SARS-CoV-2 seropositivity, an indicator of previous infection. DESIGN, SETTING, AND PARTICIPANTS This is a cohort study of employees and spouses who elected to be tested for SARS-CoV-2 IgG as part of an annual employer-sponsored health screening program conducted in August to November 2020. This program includes commonly assessed demographic, biometric, and laboratory variables, including total vitamin D measurement. Baseline (prepandemic) levels of vitamin D and potential confounders were obtained from screening results from the previous year (September 2019 to January 2020). Data analysis was performed from December 2020 to March 2021. EXPOSURES Low total serum 25-hydroxyvitamin D, defined as either less than 20 ng/mL or less than 30 ng/mL. MAIN OUTCOMES AND MEASURES The main outcome was SARS-CoV-2 seropositivity, as determined with US Food and Drug Administration emergency use-authorized assays. The association of SARS-CoV-2 seropositivity with vitamin D levels was assessed by multivariable logistic regression analyses and propensity score analyses.
RESULTS The 18 148 individuals included in this study had test results for SARS-CoV-2 IgG in 2020 and vitamin D levels from the prepandemic and pandemic periods. Their median (interquartile range) age was 47 (37-56) years, 12 170 (67.1%) were women, 900 (5.0%) were seropositive, 4498 (24.8%) had a vitamin D level less than 20 ng/mL, and 10 876 (59.9%) had a vitamin D level less than 30 ng/mL before the pandemic. In multivariable models adjusting for age, sex, race/ethnicity, education, body mass index, blood pressure, smoking status, and geographical location, SARS-CoV-2 seropositivity was not associated with having a vitamin D level less than 20 ng/mL before (odds ratio [OR], 1.04; 95% CI, 0.88-1.22) or during (OR, 0.93; 95% CI, 0.79-1.09) the pandemic; it was also not associated with having a vitamin D level less than 30 ng/mL before (OR, 1.09; 95% CI, 0.93-1.27) or during (OR, 1.05; 95% CI, 0.91-1.23) the pandemic. Similar results were observed in propensity score
Conflict of Interest Disclosures: None reported. Funding/Support: Quest Diagnostics provided funding for this study.
Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, and decision to submit the manuscript for publication. The funder reviewed and approved the manuscript. Additional Contributions: Jeff Radcliff, BS (Director, Global Scientific Publications and Medical Education, Quest Diagnostics), edited the manuscript; Andre A. Arellano, BS (Staff Scientist, Quest Diagnostics), helped with data acquisition; and Charles M. Rowland, MS (Director of Science, Quest Diagnostics), provided statistical advice. No compensation was received beyond usual salary.
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