Low levels of vitamin D have been tied to higher risks for COVID-19 and more severe illness, although no studies have proved that vitamin D deficiency is actually to blame.
A study published on Tuesday in PLoS Medicine suggests that boosting vitamin D levels with supplements would not help.
Researchers studied more than 1.2 million people of European ancestry from 11 countries, some of whom had genetic variants that result in naturally higher levels of vitamin D.
People with these variants did not have a lower risk for coronavirus infection, hospitalization, or severe COVID-19, the researchers reported.
Their results suggest that boosting vitamin D levels in deficient people probably would not help combat the coronavirus, and they do not believe randomized trials testing vitamin D supplementation would be worthwhile.
Other experts, however, would still like to see such trials, especially in people of African and other non-European ancestries.