CLEVELAND, OH (WOIO) - Mumps outbreaks are on the rise, and doctors think they know the reason behind it.
Most people get shots of the vaccine as a child, and don't think much about the virus after that.
In the most recent outbreak, at least 30 people have come down with the mumps in Delaware and the Philly area.
Researchers say a rise in mumps cases across the country may be due to the vaccine losing its effectiveness over time.
The Measles-mumps-rubella or MMR vaccine is usually given to children in two doses by the time they're six years old.
"When you have a vaccine that's 90 percent effective, and it's a very contagious virus, so that when it's introduced into a community, if you have more than one individuals who don't have protection against it, it really spreads really rapidly," said Dr. Camille Sabella with Cleveland Clinic.
Sneezing and coughing can spread the mumps.
Outbreaks tend to happen in places where people have had prolonged, close contact with an infected person, like a college dorm, playing on a sports team or going to the same class.
Symptoms of the mumps include fever, fatigue, chills and loss of appetite and puffed cheeks due to swollen salivary glands.
Over the past decade there's been a rise in mumps cases in vaccinated people.
New research revealed the vaccine immunity for mumps lasts about 27 years.
Doctors just updated guidelines in hopes of preventing more outbreaks.
They may now recommend a third dose of the vaccine for full protection.
"If you have not had two doses of MMR vaccine, it's never too late to get them. Certainly if you've only had one, you certainly should get a second dose. And if you've not had any then you should get two," Dr. Sabella said.
Mumps usually affects young adults now since young children are vaccinated.
There's no treatment for mumps, but you should call your doctor if you think you have the virus.