Mumps is making a comeback, even with people who have been vaccinated against the disease.
The New York Times reports that mumps outbreaks are on the rise, with more than 6,000 cases of mumps reported in the United States last year. That’s the highest number of mumps cases reported in the past 10 years. For some perspective, in 2010 the number of cases was down to the hundreds.
Most of the recent cases have occurred in outbreaks. A large outbreak in Arkansas, for instance, affected primarily 18-22-year-olds. The majority of those that were infected had received the mumps vaccine when they were children.
More from FORTUNE
While two doses has been standard for years, there’s now some who think that immunity to the disease fades over time. In the case of recent outbreaks, a third dose has been given to those that have or will be potentially exposed to the disease to some great results.
That said, with the absence of an immediate threat, doctors still think two doses of the vaccine as a child is enough to last most people a lifetime.