Vitamin D levels are strongly, inversely correlated with COVID-19 infection Original paper

Vitamin D has a number of effects on the immune system, and studies have shown a relationship between low vitamin D and increased risk of COVID-19 infections and mortality.

This retrospective cohort study analyzed patient records from 191,779 participants from all 50 U.S. states and the District of Columbia who received RT-PCR COVID-19 tests. Test results and vitamin D levels were evaluated and groups were stratified on the basis of age, sex, race, and latitude.

There was a strong, inverse correlation between vitamin D levels and COVID-19 infection rate, with rates of 12.5%, 8.1%, and 5.9% for participants with deficient (less than 20 ng/mL), adequate (30–34 ng/mL), and high levels (more than 55 ng/mL), respectively. While this relationship was found in every demographic group, absolute infection percentage was higher in people in the northern states when compared to the central and southern states, and infection rates were highest in Black non-Hispanic people and lowest in white non-Hispanic people, with Hispanic people in the middle. Finally, people under 60 had a higher rate of infection than people over 60, and men had a higher rate of infection than women.