Dr. Daniel McCartney:

There are quite large studies from the USA and Israel, in particular, on the risk of SARS-CoV-2 infection. A study of 500 patients from Chicago, 71 of whom tested positive for Covid-19, revealed that a person who was deficient in vitamin D was 77% more likely to be SARS-CoV-2 positive. A larger study from the US of 192,000 people-----