The vaccine only works in individuals who have never been exposed. That's why the very young get it. Mathematical probabilities show that as a person goes past 26, the odds are they have had some contact with it. Hypothetically, if her immune system clears it in the past it should continue to do so, until perhaps some point in very old age when all of our immune systems become increasingly incompetent. The vaccine does not clear existing infections. It creates an antibody that prevents them from happening in the first place. This mechanism only works in NEVER EXPOSED individuals. Ergo, if she has been exposed it will have no efect.

Brian, stage 4 oral cancer survivor. OCF Founder and Director. The first responsibility of a leader is to define reality. The last is to say thank you. In between, the leader is a servant.