I don't want to hijack the thread into a COVID debate, but yes, I do believe Vitamin D is helpful in preventing bad COVID outcomes. In my own anecdotal evidence, I caught COVID in June 2022 at the WSOP, and my symptoms were so weak that I was certain it was a mild cold. On the "worst" day of it (when I still thought I had a cold), I was able to move all of my heavy luggage between hotels in the 110 degree heat!
Only when I finally took a PCR test the following day did I see it was COVID, and at that point I isolated.
Anyway, I have been taking daily Vitamin D for the last 5.5 years, and I think there's a good chance that helped make my COVID mild.
However, you can't blame this on big pharma because COVID is new, and thus a lot of things about it will be missed. I will admit that studies about Vitamin D are probably not the priority, because there's no money in them. However, I don't think it's a coverup.
Cancer is the #2 cause of death in the US. If Rick Simpson Oil really could cure Stage 4 Cancer, the word would get around quickly, and it would be worth trillions of dollars. But it hasn't, and it's not.