>>> 2. Death rates in countries with high incidence of vitamin D deficiency e.g. Belgium, Italy, versus those with low levels (Scandinavia even Sweden, who eat oily fish and supplement/fortify).
if you don’t mind expanding on this, Germany however have very low fatality rate, yet for data as of 2015 they have the same level of vit D deficency as Italy
Since we’re comparing the mean of several numbers, and there are many factors other than vitamin D influencing those numbers, I think it’s a priori not surprising that there are exceptions.