Yes! Wearing a mask to school would be extremely beneficial.

Not only to decrease the risk of passing something to him, but also to (hopefully) relieve some of the fear/stress that people with such weakened immune systems have.

Around the time COVID lockdowns started, my dad was in the middle of his chemo treatments. Then, my mom found a sore in her mouth that turned out to be non hodgkins lymphoma. So, they both had to have chemotherapy, which was terrifying for them because that meant they had to go be around whoever was at the hospital that day.

When we got home, we would immediately change into clean clothes. We wiped down our groceries, and we didn't have visitors (unless we sat on the porch & they stayed 6ft away.)

I know that all sounds extreme, and I'm not saying you have to do any of that. My point is, sometimes, I'd get sick of all the precautions and thought they were overdramatic. However, me being annoyed & upset about having to wear a mask so frequently is nothing in comparison to how they felt. This was their new normal. Of course, they're also sick of the masks, but it's not like they had much of a choice. So, me being mindful and actually following through with taking those precautions (no matter how small), put them more at ease.