That's interesting. People were taking supplements for this last year, until studies came out saying it doesn't make an impact. Now it looks like another reversal.
Full title: <i>COVID-19 mortality risk correlates inversely with vitamin D3 status, and a mortality rate close to zero could theoretically be achieved at 50 ng/ml 25(OH)D3: Results of a systematic review and meta-analysis</i> (Borsche, L., Glauner, B., von Mendel, J.).<p>> <i>Research shows that blood calcidiol (25(OH)D3) levels correlate strongly with SARS-CoV-2 infection severity [...] There is open discussion regarding whether low D3 is caused by the infection or if deficiency negatively affects immune defense [...] The two datasets provide strong evidence that low D3 is a predictor rather than a side effect of the infection</i><p>--<p>As a parallel poster notes, there had been diverging results from different studies. It would be interesting, not only useful, to clarify the reasons of the divergence.