I’m trying to keep the worry at bay. As a mother I hate the idea of him getting sick - especially away from home. I’m a bone marrow transplant patient. So, if he’s sick, I suppose I got a few years that I never would have had. (I can’t live in fear. If it’s not this illness, it will be another. It won’t take much to take me out). But, he’s 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.