When I heard the original report on vitamin d deficiency and getting seriously ill from COVID, my first thought was people who have sedentary lives tend not to

When I heard the original report on vitamin d deficiency and getting seriously ill from COVID, my first thought was people who have sedentary lives tend not to be outdoors been active. I’ll add an assumption that this may also follow with another correlation that diabetics suffer more from COVID for perhaps the same sedentary reasons. Might be nonsense but correlation doesn’t have to mean cause - arguing against myself and bad science. Any opinions from a clinician?