Mumps outbreak at Fordham University -- every affected student had been vaccinated/ ABC

From ABC News in NYC:

The outbreak of the mumps at Fordham University has spread from one campus to another.

There are now 13 reported cases, 12 at the Rose Hill campus in the Bronx and one at the Lincoln Center campus in Manhattan.

 The symptoms are similar to the flu, but the virus can also cause painful swelling.

All of the infected patients had the mumps vaccine, but doctors say it's not 100 percent effective...

From TechTimes:

Most kids in the United States receive mumps-containing vaccine but vaccination does not give guarantee that the disease will be avoided. "Studies suggest that the mumps vaccine is 80% to 90% effective," the NYC Health Department said. "That means that for every 100 people vaccinated, 80 to 90 of them will be fully protected, but 10 to 20 are at risk for the disease." 

Health experts also said that vaccination does not give 100 percent protection. Dana Saltzman, a disease specialist, said that virus-induced immunity against a disease can wane. "The immunity that's induced by the virus starts to wane. They believe that it holds until at least late teenage years, but then it starts to wane," Saltzman said. "There's no way to predict who's going to lose their immunity or not."