More than two months ago, a nasty mumps virus triggered fever, headache and painfully swollen glands among a handful of students at Ohio State University. Now the outbreak has ballooned to 234 cases at last count, and has spilled into the surrounding community in Columbus, Ohio. Columbus officials are calling it the city's biggest outbreak since the development of the mumps vaccine in the 1940s," WOSU reporter Steve Brown [said]. "It even pushed them to open a new clinic." So far, most of those infected are students or workers at Ohio State, Brown says. And here's what's surprising: Many of those who got sick had previously been immunized against mumps via one of the top weapons against childhood diseases: the MMR vaccine. That's a two-dose shot most of us got when we were kids to protect against three diseases - measles, mumps and rubella. A young woman in New York caught the measles in 2011 even though she, too, had been vaccinated, scientists reported last week. "Measles Mary," as Science magazine her, also spread the virus to four others. Why can you still get the mumps and measles even if you're vaccinated? Measles is a terrific vaccine. If you get two doses, it's predicted to protect 99.99 percent of people for life. The mumps vaccine, on the other hand, is not so good. The protection rate varies from study to study. But it's usually in the mid-80s. Both vaccines, for mumps and measles, are tamed versions of the viruses. The viruses aren't killed but what we call attenuated, live viruses. The outbreak at Ohio State University is due to "vaccine failure," not declining immunization rates in the U.S.