The finding that the COVID-19 positivity rate in the United States varied from 6.5% for vitamin D concentrations between 40 and 50 ng/mL, to 11.3% for values of 20 ng/mL, may result from the effect of vitamin D in reducing virus survival and replication by induction of cathelicidin and defensins, as well as by increasing free ACE-2 concentrations, thus preventing COVID-19 from entering cells through the ACE-2 receptor [116]. The gene discussed is ACE2; the disease is COVID-19.