Both my husband and I were microbiologists and are often criticised by our children over our rather careless attitude to hygiene. This is quite common among microbiologists as we know where the real risks are, but don’t try to disinfect everything in sight. Despite, (or maybe because of) our not very clean house, our children weren’t sick very much growing up, apart from usual childhood illnesses. We did give them every vaccine offered and would have got chickenpox vaccine if available as it can be very nasty.
Many children pick up bugs when they mix with other children and sometimes pass them on to adults, which is annoying, but not dangerous unless the person is immunosuppressed. Anxiety and stress can also lead to illness, including suppressing immune system, so worrying about the bugs may increase your risk of catching something, Ethelbags.