This isn't really a 7th option because it overlaps with some of the previously mentioned ones, but perhaps individuals who don't supplement with vitamin D are more likely to catch Covid-19 because they also don't take other precautions like wearing masks.
Anecdotally it seems those I know who are most concerned about Covid-19 know all about the possible link with vitamin D and are taking supplements while also being careful by wearing masks, sanitising etc.
Recently I keep seeing references to protecting oneself by wearing a mask.
When did the narrative shift from "wear a mask to limit transmission to others in case you might be infected and asymptomatic" to "wear a mask to protect yourself"?
Assuming we are talking about the usual surgical / cloth masks here (not N95 etc), is there any evidence that they protect the wearer?
We all know that mask wearing and the science (or lack of it) to support it has become ridiculously politicised, but I'm curious if there's any evidence behind this particular shift.
This, and as someone who recently found out that they have a severe vitamin D deficiency, I was surprised to know that it's not something normally checked for in yearly blood tests.
Check the videos on Dr John Campbell's (PhD nurse educator in the UK) web site. The UK national health service has good medical records that can be cross-referenced and cross-linked every which way. Someone examined the historical records, found a reasonably large number of persons who had vitamin D levels checked before the pandemic, and checked those statistics vs the Covid-19 experience of the same people. (Imagine living in a country where that could happen.) IIRC, this did find some benefits wrt COVID-19 of not having a very low vitamin D level.
