https://news.ycombinator.com/item?id=24366006
I've been monitoring HN for Vitamin D info very closely.
(Can't find the HN discussion link at the moment, unfortunately -- it didn't point to that particular link!)
Worth noting that this RCT was for bolus supplementation of Vitamin D3 at some point in their hospital stay, and excluded patients already supplementing with D3.
This study stands in stark contrast to the earlier pilot out of Spain: https://www.sciencedirect.com/science/article/pii/S096007602... -- though as noted, this was not D3 but rather Calcifediol (a D3 metabolite), and a much smaller study.
Proper Vitamin D level should be reached _before_ contact with the virus. Then the data would be valuable and helpful. Theirs data doesn't show much, imho.