[Republican Wildcat]

Correct. The body reacts to the vaccine in many which can cause some of the symptoms of the disease briefly. It isn’t pleasant, but it beats getting the full blown disease if the vaccine works.

[Buckeye McFrog]

It isn’t pleasant, but it beats getting the full blown disease if the vaccine works.

IF the disease is sufficiently deadly. Like anything else in life vaccines require some cost-benefit analysis. Smallpox? Sure. Historically it's been a proven killer. Mumps? Why? They've never killed anybody.