It's probably just a confounding variable. Having more Vitamin D probably means that you are getting more outside activity and/or have a better diet. Both thin

It's probably just a confounding variable. Having more Vitamin D probably means that you are getting more outside activity and/or have a better diet. Both things have a protective effect against things like Covid in the way of better cardio and immune system. So, I would say that the link is very weak at best and probably not related to vitamin D directly.