This paper cites 10 other papers, two of which are essentially the same paper. The author also has additional papers claiming that Vitamin D helps prevent COVID mortality using a "ecological integrative approach." His papers also all seem to be lacking concrete meta-analysis and discussion of other approaches and clinical data.
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.
"The Big Vitamin D Mistake is a concise advocacy editorial, not a definitive study. Its central thesis—that we all need ~10× more vitamin D than current RDAs—is not supported by subsequent large randomized trials or by regulatory reviews. Use it, if at all, as a conversation starter about DRI methodology, not as a basis for clinical dosing."
Edit: You can also click on his name in the original post (or the link above) and see all the papers in pubmed authored by him.
Edit 2: These two papers:
Veugelers PJ, Ekwaru JP. A statistical error in the estimation of the recommended dietary allowance for vitamin D. Nutrients. 2014;6(10):4472–4475. - PMC - PubMed Veugelers PJ, Ekwaru JP. A statistical error in the estimation of the recommended dietary allowance for vitamin D. Nutrients. 2014;6(10):4472–4475. - PMC - PubMed
and
Heaney R, Garland C, Baggerly C, French C, Gorham E. Letter to Veugelers, P.J. and Ekwaru, J.P., A statistical error in the estimation of the recommended dietary allowance for vitamin D. Nutrients 2014, 6, 4472-4475; doi:10.3390/nu6104472. Nutrients. 2015;7(3):1688–1690. - PMC - PubMed
From what I can tell, the "ecological integrative approach" is referring to the approach used in the research of that paper, not on how Vitamin D acts in relation to COVID
> Following an ecological integrative approach, we examined the associations between published representative and standardized European population vitamin D data and the Worldometer COVID-19 data at two completely different time points of the first wave of this pandemic.
and
> Thus, a major limitation of our ecological approach is that we had to rely on published - but perhaps not always completely representative - data on the vitamin D status of the populations in Europe.
Right, I was criticizing the approach. Edit: specifically the fact that the paper has no discussion of how the meta-analysis data was prepared, processed, or how they made sure it was complete.
I would agree with you if this paper was citing... more papers. Since there are so few and one of the citations is a concurrence with the paper with actual data work, then it harms this paper.
Either the author didn't do a literature review before publishing, isn't well versed in the field, or chose not to cite works which may not agree with their results. Neither of which reflects well on the author.
Seems... like a quack.