Recently, I've read several articles noting the relationship between germs and babies and that relationship to allergy and asthma. Apparently, babies who were introduced to germs common to going to a farm were much less likely to get asthma or have serious allergies.
This is really good to know, especially for some new parents who try to have their baby avoid germs at all costs. It does appear that babies need to build up their own tolerance to common germs. Obviously, parents should not expose baby to someone with an illness or disease that is communicable. But in all things, that age old addage "Keep all things in moderation" still seems to apply.