Since the pandemic, there was certainly noise about Vitamin D deficiency and COVID-19 death correlation that the NIH decried as unsubstantiated. Fair enough. Since then, quite a bit of data has been collected.
There are a few hundred PHDs^1 that agree that Vitamin D deficiency increases COVID 19 mortality (nowhere is prevention mentioned) in the US, with no EU overlap that I could see from casual review.
Maybe I'm taking sides here, but I think the data is supported, even if the NIH papers are flawed. Funding what many people assume to be a null hypothesis, is not popular so there may never be research that is convincing, for most.
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.
There are a few hundred PHDs^1 that agree that Vitamin D deficiency increases COVID 19 mortality (nowhere is prevention mentioned) in the US, with no EU overlap that I could see from casual review.
Maybe I'm taking sides here, but I think the data is supported, even if the NIH papers are flawed. Funding what many people assume to be a null hypothesis, is not popular so there may never be research that is convincing, for most.
^1 The signatories are not a comprehensive list, but one list among others: https://www.onedaymd.com/2020/12/vitamin-D-COVID19.html