I’ve been taking D3 supplements during the fall and winter (basically start when “daylight savings” time starts) for years, as there’s been hints and signals that vitamin D deficiency is implicated in all sorts of maladies.
That said, this is one more piece of evidence that you just don’t want to be vitamin D deficient, but there are still questions. One being, is there something else common to those individuals with < 50ng/ml, or conversely, with > 50ng/ml besides their serum D levels? Age, fitness level, amount of adipose tissue, any other confounders?
The authors may have corrected for that, didn’t read the whole paper.
If one has excess vitamin a, the body uses vitamin d faster.
It might be that people with excess vitamin a do worse against the wuhan coronavirus, and that caused this result.
They are saying: “Mortality rates from clinical studies were corrected for age, sex and diabetes.”