Comedian and cardiologist with laudy credentials. Maybe he has a good grasp on Covid but I seriously doubt it. He has a platform and gets to shoot his mouth off and get a few retweets.
First problem is he creates a false equivalency. Vaccine and autism is so incredibly debunked only the most fervent adherents still bunker up and hold to the "truth". Flat earther type stuff. Just using it in the tweet is taking supplement supporters into the same radical category. Is there a lot of crossover in those belief groups? Probably. But a "scientist" shouldn't use this falacial logic.
The second problem is labels and groups. Use of the word "truthers" conjures up Obama birth conspiracy and QAnon comparisons. He has now grouped supplement supporters with anti-vaxxers and far right conspiracy adherents. He gives himself some wiggle room by using the "people who think .... solve all ills". He doesn't back himself completely into the corner with that statement.
The problem with his statement is that research does suggest Vitamin D levels and supplementation may play a significant role in Covid morbidity and mortality. The correlation is consistent. And there are studies to suggest supplementation can mitigate (not cure) Covid severe disease. It's not completely settled but consensus is moving that direction. There are multiple papers that support these findings. Unfortunately, Vitamin D appears to be needed prior to infection. High doses when you start feeling sick are likely not going to help. This also appears to be supported in research. I could link up a couple of dozen of articles from good journals on this topic. And as any critical thinking physician will tell you, there will be a myriad of things we can do to prevent or treat Covid.
Supplementation is a tricky subject and overwhelmingly does not show to create massive health benefits. I was a strong supporter of supplemental Vitamin D years ago for some osteoporosis work I do but good data has shown it is largely ineffective in 95% of cases. I have backed off my strong support accordingly. I pretty much shrug my shoulders when patients ask about multi-vitamins for their families. It is hard to be vitamin and mineral deficient in our country if you any sort of fortified or natural foods. And studies that show us that Zinc and Vitamin C don't do much if anything for Covid.
You post pretty good stuff but IMO, Dr. Francis' tweet was unbecoming of a physician. He could have gotten his point across without going Bill Maher.