Vitamin D increases the expression of ACE2 receptors but also modulates the genetic expression of renin, resulting in a smaller effect of renin on its receptor; that is, there is less chance of pulmonary vasoconstriction and myocardial injury, less renal perfusion, pulmonary edema, and renal and myocardial failure seen in severe COVID-19 [41–44]. The gene discussed is REN; the disease is COVID-19.