Borsche and Glauner don't seem very trustworthy, but it is no secret that a vitamin D deficiency is correlated with higher mortality. The comorbidities that are

Borsche and Glauner don't seem very trustworthy, but it is no secret that a vitamin D deficiency is correlated with higher mortality. The comorbidities that are associated with Covid-19 mortality are, pretty much, all correlated with vitamin D deficiency. The real question is, if someone is obese, or has diabetes, or has CKD, or is old, what is it that is making them more likely to die of Covid-19? Is it a vitamin D deficiency or some other related issue? and can supplemental vitamin D help? My guess is that it helps more than hurts to supplement vitamin D if you are deficient or insufficient. I'd also guess that it is no miracle cure like Borsche and Glauner seem to want people to think.