Back in the days before vaccines, you know what people did with kids who had "childhood illnesses?"
They kept them home, in bed, for the entire course of the illness. Because that was what you did.
When all those diseases were in circulation, people KNEW they could be serious. They didn't mess around, they didn't send them to school, they didn't take them grocery shopping, they didn't take them to Halloween parties, and they didn't take them door to door around the entire neighborhood.
They just didn't. Sick children were kept at home. In fact, in many municipalities, sick children were officially put under quarantine by local public health officials. My grandfather was a public health agent in the days before (most) vaccines and before antibiotics. One of his jobs was to go to the houses of people with certain illnesses and post the big, official, QUARANTINE signs on their doors.
If you're not going to vaccinate, if that is the world you want, then you need to LIVE IN THAT WORLD. That world where those diseases are recognized as commonplace BUT potentially serious to certain people, and where sick children are kept home and treated as sick, to help their bodies recover.