Having young kids myself, I can say pretty confidently that kids are going to expose themselves to quite a lot of germs no matter what precautions we take, shor

Having young kids myself, I can say pretty confidently that kids are going to expose themselves to quite a lot of germs no matter what precautions we take, short of putting them in solitary confinement in clean rooms. So I think it's possible that precautions reduce viral and bacterial exposure, but since they don't completely stop it, immune systems may still get enough exposure to build immunity to things while still not getting enough exposure to actually make them sick.