Associations between predicted vitamin D status, vitamin D intake, and risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) severity.

Vitamin D supplementation was associated with a lower risk of COVID-19–related hospitalization. There was an association between exposure to UV-B or UV-A, independently of vitamin D, and SARS-CoV-2 infection.

• Higher predicted 25(OH)D concentrations, but not vitamin D intake, were associated with a lower risk of SARS-CoV-2 infection. 
• Participants in the highest quartile of UV-B and UV-A also had a lower risk of SARS-CoV-2 infection compared with the lowest.  
• High intake of vitamin D from supplements (≥400 IU/d) was associated with a lower risk of hospitalization. 

A sample of 1768 subjects from a large longitudinal study of female nurses.

• Vitamin D status was determined through a prediction equation and not actual measurement of vitamin D. 
• Predicted 25(OH)D concentrations and vitamin D intake were based on data from 2015, 5 y prior to the pandemic. Many subjects may have started taking vitamin D supplements in that time. 
• There was some adjustment for several potential confounders, including lifestyle factors and comorbidities, but the possibility of residual confounding cannot be eliminated.  
• The majority of COVID-19 cases in this study were mild in severity, making the impact of vitamin D on more severe COVID-19 risk impossible to determine in this study.  
• There was a lack of diversity in the sample in terms of race and age making it difficult to generalize to other racial/ethnic populations. 

“In conclusion, we found that predicted 25(OH)D concentrations were associated with a lower risk of SARS-CoV-2 infection. This association was observed specifically for asymptomatic, but not symptomatic, infection. Vitamin D supplementation was associated with a lower risk of COVID-19–related hospitalization. These data also support an association between exposure to UV-B or UV-A, independently of vitamin D, and SARS-CoV-2 infection; thus, results for predicted 25(OH)D need to be interpreted cautiously. Additional research is needed, particularly high-quality randomized controlled trials, to guide the use of vitamin D supplementation in the prevention and treatment of COVID-19.” 

• This study analyzed data from periodic surveys (May 2020 to March 2021) within the Nurses’ Health Study II.  
• Among 39,315 participants, 1768 reported a positive test for SARS-CoV-2 infection.  
• Usual vitamin D intake from foods and supplements were measured using a semiquantitative, pre-pandemic food-frequency questionnaire in 2015.  
• Predicted 25-hydroxyvitamin D [25(OH)D] concentrations were calculated based on a previously validated model including dietary and supplementary vitamin D intake, UV-B, and other behavioral predictors of vitamin D status. 

Ma W, Nguyen LH, Yue Y, Ding M, Drew DA, Wang K, Merino J, Rich-Edwards JW, Sun Q, Camargo CA, Giovannucci E, Willett W, Manson JE, Song M, Bhupathiraju SN, Chan AT. Associations between predicted vitamin D status, vitamin D intake, and risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) severity. Am J Clin Nutr. 2022 Apr 1;115(4):1123-1133. doi: 10.1093/ajcn/nqab389. PMID: 34864844; PMCID: PMC8690242.