L.T.
Don't keep him from catching them. You won't be doing him any favors by keeping him from catching them. The best way for him to build an immunity is to be exposed to minor illnesses like colds, and minor episodes of other illnesses like the flue, measles, and chicken pox. Many new mothers do not realize that by trying to keep their children from getting chicken pox and the measles, they are leaving them wide open to much worse illnesses like, German measles, and the pox later in their life which can leave them sterile or even dead. Even contracting regular measles or chicken pox later in life can leave an adult sterile or dead.(For some reason these diseases hit adults much harder than they do children.) By allowing the body to be exposed to minor illnesses, we build up immunity to much worse illnesses. An example showing this can be taken from the past, where milk maids exposed to cow pox would often be immune to catching the pox.