Derivative of 7-dehydroxycholesterol formed by ULTRAVIOLET RAYS breaking of the C9-C10 bond. It differs from ERGOCALCIFEROL in having a single bond between C22 and C23 and lacking a methyl group at C24. Some experts recommend maintaining recommended levels of vitamin D intake during the COVID-19 pandemic to maintain bone and muscle health and avoid deficiency. Efficacy of vitamin D supplementation in the prevention or treatment of COVID-19 has not been established.