Vitamin D has the counterintuitive effect of lessening the severity of COVID-19 based on the up-to-date umbrella review [45], despite the initial inconsistency in the results, which could be explained by genetic polymorphisms in several genes associated with vitamin D metabolisms such as CYP2R1 rs10741657, DHCR7/NADSYN rs12785878, carriers of CYP2R1 GG and DHCR7/NADSYN TG+GG genotypes, and DBP polymorphisms rs4588 and rs7041[46]. The gene discussed is CYP2R1; the disease is COVID-19.