The CDC reported that 2016 was the worst year for mumps in a decade—and 2017 isn't looking any better.
You don't hear about people getting mumps very often in the U.S. anymore, which is largely due to the mumps vaccine that became available in 1967, and that since 1971 has been part of the measles-mumps-rubella (MMR) vaccine. Since then, the number of cases per year has sharply declined since most children get two doses of the vaccine, first between 12 and 15 months and then again between ages 4 and 6. There are, however, isolated spikes every now and then. But according to the Centers for Disease Control, we are in the middle of a major spike right now: More than 1,200 cases of mumps have been reported so far in 2017. This comes after 2016 logged more than 5,300 cases—the highest number of cases since 2006. Compared to the 1,329 cases recorded in 2015, that's a pretty big jump.
Many of the 2017 cases are continued outbreaks from 2016, according to a CDC rep, as reported by USA Today. The high number so far in 2017 is worrisome, but because mumps outbreaks are unpredictable, it's unclear whether this level of mumps cases will continue throughout the year.
If you're not familiar with mumps, it's a contagious viral disease that is best known for the puffy cheeks and swollen jaw that it causes, according to the CDC. While some people who are infected never experience symptoms, others experience fever, headaches, loss of appetite, and swollen salivary glands. Since mumps is a virus, it cannot be treated with medication. Most people recover in a few weeks with lots of rest, but there can be complications (mainly in adults) like swelling of the brain, spinal cord, testicles, ovaries, and breast tissue. Death from the disease is extremely rare, but it's possible with a complication like inflammation of the brain or spinal cord.
While many people are vaccinated with MMR when they're young, the vaccine can lose efficacy after about 10 to 15 years, which is right around college age for most people. The initial two doses of the vaccine have an effectiveness rate of 88 percent, meaning you're not completely protected against the virus even if you've been vaccinated. While some opt to get a third booster, not everyone does, and it's not required the way other boosters are for college admission. It's most common for these outbreaks to occur on college campuses and in similar crowded environments. The virus is transmitted through saliva and mucus, so coughing, sharing drinks, and kissing can play a role in passing along the infection. (Related: We may soon have a universal flu vaccine.)
So what's the cause of this sudden increase in cases? Paul Offit, M.D., a professor of pediatrics in the division of infectious diseases at Children's Hospital of Philadelphia, told WSJ that "while most measles outbreaks these days are the result of large populations not getting vaccinated, mumps cases are more often due to faded immunity among those who were vaccinated years ago." So basically, there's not much you can do except try to make sure your vaccine hasn't worn off. Still, Offit doesn't believe that having people get a third booster shot is the answer to preventing the spread of mumps. It might help prevent some people from getting the disease, but it's not effective if an outbreak is already occurring, which is likely why the CDC has not made a formal recommendation that everyone get a third vaccine. As of now, it's TBD exactly what can be done to keep people from catching the disease, but it's safe to say that if you know someone who has it, you should steer clear—even if you're up to date on your vaccines.