Im trying to keep the worry at bay. As a mother I hate the idea of him getting sick - especially away from home. Im a bone marrow transplant patient. So, if hes sick, I suppose I got a few years that I never would have had. (I cant live in fear. If its not this illness, it will be another. It wont take much to take me out). But, hes strong and healthy.
Both of you need to look into taking D3 if you can.
You would obviously have to ask your doc, he could probably just start taking it.
ALSO, for him, have him get sunshine when he’s at a locale far enough south for that to work to make D3.