A lot of home-schooled kids are exposed to lots of pathogens. They still play with other kids, all the neighborhood kids have all the school germs and expose the other kids. Homeschooled kids also often belong to groups that do things together, field trips, phys ed, stuff like that. Unless kids are totally isolated, they will be exposed and build up normal immunities. (I did the homeschooling thing for awhile. There wasn’t extra sickness from being in school)