Aggressively identifying and treating people with vitamin D deficiency is one potential strategy to reduce the risk of COVID-19. As outlined in the BMJ review, regularly taking oral vitamin D3 mitigates infection, although the optimal oral dose is debatable. Bolus doses do not appear to provide benefit against infection, possibly through a dysregulation of vitamin D metabolism.
There may be a simple yet effective alternative. Since exposing the whole body to bright sunlight can provide long-lasting and rapid correction of deficiency, this may provide a critical boost to host immune defenses. Lacking definitive research, any risk of exposing the body to sunshine while sheltering in place is clearly outweighed by the risk of COVID-19. End quote
