The website vdmeta.com provides a meta-analysis of all clinical vitamin D trials regarding Covid.

It can be seen that early treatment with vitamin D significantly prevents death, ventilation and severe cases.

However, the overview also has a downside. It does not tell anything about the initial and achieved vitamin D blood serum level and the type of admission (as in oral vitamin D3 or intravenous calcifediol).

@Sunfluencer