Could it also be that vitamin D levels indicates some other pathology and maybe supplementation with vitamin D itself doesn't do anything for chances of getting infected?
(We are more speaking about servility of symptoms then becoming infected.)
But yes, it could totally be the case.
It also might not be the case.
It also might be anywhere in-between, like supplements help but the a negligible degree.
As long as we don't have statistically significant studies showing causation we can't say for sure.
But then what we can say for sure is that any deficit puts a burden on you body and any burden makes it harder for you if you get some other massive health problems. Even if just to a very small degree.
So if you have a vitamin D deficit you should fix it especially if you also have COVID (EDIT: or any potentially more dangerous illness).
But if you don't have a deficit it's questionable if taking vitamin D will do any help.
Well, yes Vitamin D does attenuate immune response. However the science on citokine storms is most probably wrong and not associated with covid, and at this point has become hard to stop the information train on. If there's one thing I've learned about people during covid is that the game of telephone played over a short time period to get something solved is a huge issue.
