Defensins and cathelicidins are antimicrobial peptides and a crucial part of the innate immune response. They are powerfully upregulated by vitamin D. This review discusses their specific role in lung immunity and inflammation, also with regard to animal models of SARS-CoV-1, as well as their relation to vitamin D.

Looking at the disproportionate number of cases among people of color in the U.S., vitamin D deficiency is likely to play a role in increasing the susceptibility to Covid-19.