There's a lot more data here that specifically tested about vitamin-D levels in early and late stages: http://agingbiotech.info/vitamindcovid19/ http://agingbio

There's a lot more data here that specifically tested about vitamin-D levels in early and late stages: http://agingbiotech.info/vitamindcovid19/ http://agingbiotech.info/vitamindcovid19/ I agree that causation hasn't been completely proven, but there's a lot of data to support it could be causative.