Question 32 Jorge works at a school that has had an outbreak of the measles. He is worried that maybe his childhood measles vaccine didn't work, or has worn off, or something. You order an antibody titer and it turns out there are already low levels of antibodies against measles in his blood. Why? Jorge got measles antibodies from his mother's milk when he was an infant and they are still around in very low levels. The vaccine triggered an activation of the specific immune response to the measles and left memory B cells scattered around the body making low levels of measles antibody. None of these explanations makes sense. Jorge has already been infected with the measles and his body is busy fighting it off.