The problem is this: if you ask a doctor, they will tell you "of course you shouldn't be deficient; get tested and supplement if necessary". But lots of people

The problem is this: if you ask a doctor, they will tell you "of course you shouldn't be deficient; get tested and supplement if necessary". But lots of people are deficient because of modern lifestyles and won't bother with the test. So the better advice is that most people should supplement based on a few simple criteria. Why aren't public health officials saying that? It's ridiculous to go through a pandemic with the same old useless advice. And if you push vitamin D, now you're a conspiracy theorist. Just take vitamin D in reasonable and get tested occasionally. Stop if you are on the high side.