[aauchter]

Interesting but a there's a decent chance of correlation not causation. Unhealthy people and people over 65 (i.e. those most susceptible to serious COVID complications) are the same group that are most likely to be Vitamin D deficient. The primary source of Vitamin D is sunlight. People over 65 tend to stay indoors, etc. People with darker skin are also more prone to D deficiency due to increased melanin, but also have higher rates of obesity, more likely to suffer from diabetes, are more likely to live in cramped conditions, etc.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3447083/ https://www.cantonmercy.org/healthchat/42-percent-of-america... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6075634/

[KerryJones]

There's a lot more data here that specifically tested about vitamin-D levels in early and late stages: 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.

[nostromo]

From the paper:

> After correction for age, sex and previous illnesses, the risk of death is 10 times higher for people with vitamin D deficiency.

That said, it could still be correlative and not causative with some different underlying health issue.

[wtetzner]

> That said, it could still be correlative and not causative with some different underlying health issue.

On the other hand, maybe Vitamin D deficiency is the cause or one the causes of those underlying health issues.