Do we need germ exposure to keep our immune system strong?
Without knowing what is meant by “germs” (any type of microbe or only harmful microbes?) and what is meant by “strong” this is a difficult questions to answer.
In the C20th, its assumed meaning was “Does exposure to harmful microbes strengthen our immune system to fight infections”? But in 1989 the hygiene hypothesis was published proposing a link between rising rates of childhood allergies and living in cleaner homes with higher standards of personal cleanliness.
This was an attractive concept to the media and public who interpreted it as further proof that our modern obsession with cleanliness and hygiene is not only weakening our ability to fight infection but also our ability to “fight off” allergies.