Those born after 1957 and had their MMR vaccine before 1968 probably have no immunity because the government used a not-very-effective killed-virus in the vaccines. (Those born before '57 are presumed to have natural immunity.) Some only received one dose of the modern MMR (after '68) and really needed that second dose due to a number of factors (but others don't). Don't listen to anyone's "personal" or "political" opinions when it comes to vaccines --make a fact-based decision and then live or possibly die with it.