[FiftyBelow]

In theory, a vaccine actually gives you a dead flu virus or a very small dosage of the live pathogen that has had been altered. Your immune system is supposed to respond to these by having particular cells develop antibodies. In the long run your body is supposed to have these particular antibodies in your bloodstream. When the particular antigen enters your system again, the antibodies will there to recognize it and ultimately bind it to the antigen, marking it for destruction by certain cells. At least thats all I can remember... haven't taken Cell Biology since 1st year.

So vaccines don't develop 100% immunity but increase the chances that your body will develop the antibodies necessary with less chances of having an individual succumb to the disease. That said, I'm still a little skeptical with the amount of testing that has went into the vaccine. Normally, there is a significant and lengthy process that goes into testing, but this vaccine (for obvious reasons) appears to have been rushed.