I'm 25, received two Hepatitis B vaccines when I was 11-12. I guess as a part of my first prenatal blood tests they checked and the results came back that I am not vaccinated against Hep B. ? The doctor said it happens on the rare occasion that the vaccine does not stick and a third dose is required. Never heard of this... anyone else? Please share your stories or what you know :) thanks! I did google it, but could not seem to find much on the matter. I would have never known I wasn't vaccinated anymore, had they not tested for it.