This is true. A TRUE vax, is designed to allow your bodies NATURAL anti-body system, to produce the needed anti-bodies for most bugs, by giving it a weakened or killed version of what ever you are trying to treat. It needs to figure out the receptor points and proteins needed to combat it. Essentially, designed to allow your body to do its job. Essentially, allowing your body to do its thing more effectively, before being overrun by the illness, that's where the weakened or killed part comes in.
Remember, a virus INVADES a hosts cells, and uses the hosts own cells to replicate, but at the same time, because it is a cell natural to the hosts body, the hosts natural immune system thinks its a normal cell, thereby protecting the virus that's inside the cell membrane.
Think about that.