According to new government data, the U.S. is experiencing more mumps cases this year than the country has seen annually in a decade. The Centers for Disease Control and Prevention reports that, as of November 5, the U.S. has seen 2,879 cases of mumps in 45 states and Washington, D.C., this year. By comparison, there were a little over 1,000 cases reported last year.
Mumps is a highly contagious disease that’s caused by a virus that is spread through saliva and mucus. It used to cause up to 186,000 cases a year, but the measles, mumps, and rubella vaccine — better known as the MMR vaccine — brought numbers down, the CDC says. The CDC recommends that children get two doses of the MMR vaccine, but notes that it’s not 100 percent effective.
People who contract mumps typically develop puffy cheeks and a swollen jaw due to swollen salivary glands, but they also may have a fever, headache, muscle aches, fatigue, and loss of appetite. Symptoms usually appear up to 18 days after a person is infected, and most people recover completely in a few weeks, the CDC reports.
Why the sudden increase this year? Richard Watkins, M.D., an infectious disease specialist at Cleveland Clinic Akron General Medical Center, tells SELF that there are likely a few things at play. One is that some outbreaks may occur because parents made the decision not to vaccinate their children, leaving them more susceptible to contracting the virus, he says. The other is likely due to what he calls “waning immunity.” The CDC recommends that children get two doses of the MMR vaccine, with the first dose at 12 to 15 months of age, and the second anywhere between four and six, he explains. Typically, the vaccine’s effectiveness starts to decline 10 years after the last vaccine, he says.
It’s soon after this time that people go to college, where they may be exposed to mumps from unvaccinated peers, or students who attend school from abroad, where the MMR vaccine isn’t as popular, William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine, tells SELF. “If you were vaccinated against mumps and you get exposed to it in your teenage years and into young adulthood when immunity wanes, particularly in close face-to-face contact with someone, you can get a milder case of it,” Schaffner explains.
The CDC admits that the MMR vaccine isn’t perfect. “MMR vaccine prevents most, but not all, cases of mumps and complications caused by the disease,” the agency says on its website. Two doses of the vaccine are 88 percent effective at protecting against mumps, and one dose is 78 percent effective, the CDC says. That’s why outbreaks can still occur in communities where people are vaccinated — however, high vaccination rates limit the size, duration, and spread of mumps outbreaks.
Most mumps outbreaks this year have been on college campuses, board-certified infectious disease specialist Amesh A. Adalja, M.D., an assistant professor at the University of Pittsburgh Medical Center, tells SELF. “The nature of a university campus tends to allow for bigger outbreaks,” he says. “It really allows the virus to find enough hosts to get to these types of numbers.” (Harvard, for example, experienced an outbreak this spring.)
When these outbreaks do occur, people may be offered a third dose of the MMR vaccine to try to boost their immunity. “That may be something that has an increased role that we continue to see,” Adalja says. In fact, the Advisory Committee on Immunization Practices (a panel of health experts who give vaccination guidance for the U.S.) is considering recommendation of a third dose of vaccine for everyone as part of the MMR schedule, per CNN. However, they haven’t said what age they would recommend the third vaccine for.
If a mumps outbreak occurs near you, try to avoid contact with infected people, if possible. “It’s spread by direct person-to-person contact and respiratory droplets,” Watkins says (think: being sneezed or coughed on, or through kissing). You’re especially at risk if you get within three feet of someone who has the virus, Schaffner says, particularly if you’re in close prolonged contact, like being in a class together or work setting with them.
However, if you do contract the mumps, don’t panic. “It’s a short-lived illness that is not very dangerous,” Adalja says.
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