According to Prof.dr. Madarina Julia our body needs sunlight for vitamin D production

When I joined CERN in 2012, I had to pass a medical exam. It turned out I was deficient in D-vitamin. Not so surprising as I was living in the northern part of Europe, it was winter time, and I was spending most of my time in front of a computer screen... ;)

To come back to the topic, the relation between COVID and greography / population is a tough thing. There are so many ingredients in there... so that it is by far not clear for anyone. At least this is my impression.