You would probably be interested in the Andromeda Strain. There is a scene in the book where one of the doctors studying the virus gets trapped in the room when the seals fail. He panics and asks to be given a drug called Kalocin. Apparently, there had been some secret medical breakthrough where a pharmaceutical company discovered a miracle drug that killed anything on a microscopic scale in the human body. However, in doing so, it essentially turned off the human immune system, and when subjects stopped taking it, they started dying to all sorts of strange diseases that no one had ever seen before because humanity had become immune to them.