But science (not intuitition) has shown that the immune system can handle many such "onslaughts" at once with only positive results. Many, many.<p><i>the only vaccine that I've questioned is the Chicken pox vaccine. My son got it, but when I was growing up getting the Chicken pox was just part of being a kid.</i><p>So if you got it then everyone should be at risk of getting it? It's not better if we can prevent it altogether by teaching the immune system to fight it off? Chicken Pox is not necessarily harmless; do a Google search for "shingles".