Thread by @gshotwell

I think Dr. Bogoch is making two mistakes here:

1. Picking a bad prior
2. Using inconsistent evidentiary standards

https://twitter.com/BogochIsaac/status/1322923258266746881

1) Researchers often pick a general prior for vitamin D based on all vitamin D trials. There are many failed vitamin D trials for things like cancer, diabetes, or all cause mortality.

This doesn't make sense to me because we should pick out prior based on similar diseases. Covid is a respiratory virus and trials of vitamin D in the respiratory context have shown a modest benefit.

bmj.com/content/356/bm…

2) Inconsistent evidentiary standards. Lots of researchers, including Dr. Bogoch, have placed great weight on anecdotal, ecological, or mechanistic evidence to argue that cloth masks are clearly effective.

The evidence for vitamin D isn't watertight by any means, but it's a heck of a lot stronger than the evidence for masks.
shotwell.ca/posts/masks_an…

I'm sure there's a principled reason to use weak evidence for masks but require drug-style RCTs for vitamin D, but I haven't heard it yet