Should note these mdpi journals have a reputation to be garbage, look for other publications in more reputable ones before buying everything this paper says.
Not saying vitamin d has no impact, but the methodology of this specific paper may not be up to snuff.
It’s quite a jump to go from vitamin D deficiency being a frequently encountered factor in mortality to saying that it “accounts” for 9/10ths of fatal cases. I doubt a silver bullet as simple as vitamin D has been hiding for his long, so the title is too grabby.
That said, there have been plenty of studies that have brought up this link, it’s not just some pop sci trend. (Several of them are referenced in this OP study.)
There has been a recent study from Brazil that more or less found vitamin D supplements to be insignificant in treating severe cases that are late in prognosis. It’s unfortunate that loading up on vitamin D while suffering a severe case of COVID likely wouldn’t help much (if that as-of-yet unreviewed study is to be trusted), but it doesn’t write off supplements for general risk minimization.
or being bedridden due to another illness preventing you from sunning yourself.
Don’t forget the medical condition of “I’m awake before the sun rises, sitting inside at work while the sun is up, and go home when the sun has already set” syndrome
