Perhaps Dr Cohen would prefer the term "exercise your immune system". For many years and for no particular reason I have been certain that a regular exposure to bacteria, etc, help keep a person healthy. Any system works best when it's in regular use.This past year I've even seen a few articles on the subject. One by a doctor who grew up in India and emigrated to Westchester, New York was especially interesting. He said that children in India had better health than his own, pampered children. His conclusion was similar to mine.