Mumps is bad this year in the U.S. So far, more than 4,600 cases have been reported.
So experts voted on Wednesday to recommend that people at high risk of catching mumps during an outbreak get a booster dose of the vaccine, even if they've already been vaccinated twice.
Vaccine advisers also recommended a brand-new shingles vaccine — one that protects people much better than the older vaccine. They voted to recommend people use the new one, called Shingrix, even if they've had the older one.
Members of the Advisory Committee on Immunization Practices (ACIP) had hoped to get some fresh information on whether adding a third dose could help control outbreaks of mumps, which are becoming increasingly common on university campuses, as well as in church groups, community recreation centers and elsewhere.
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But there's not enough evidence to say whether it's worth the expense and effort of vaccinating large groups to control the virus, which causes mild symptoms in most people. In a few people it can cause meningitis, deafness or sterility.
"The information is limited although the limited information would indicate that the third dose does reduce your risk of getting the disease," said Dr. William Schaffner of Vanderbilt University and the National Foundation for Infectious Diseases.
"It's a good thing to do. We did it at Vanderbilt. We had a few cases. They targeted one fraternity (with vaccines)," he added. When a few cases turned up outside the fraternity, health officials used an approach called ring vaccination — vaccinating everyone in contact with someone who got sick.
"That stopped our outbreak and we didn't have any more cases," Schaffner said.
There's a mumps outbreak going on now at Syracuse University in New York and they've started vaccinating students there. All 27 confirmed cases had been vaccinated against mumps before, usually with the combined measles-mumps-rubella (MMR) vaccine.
"There is no reason to leave campus and no reason to be alarmed. The University is taking aggressive action to educate the campus community about prevention and treatment," Syracuse said in a statement posted on its website.
Last year was the worst year for mumps in the U.S. since the MMR vaccine program started in 1977, said Dr. Mona Marin of the division of viral diseases at the Centers for Disease Control and Prevention. There were 6,366 reported cases in 2016, up from 1,329 in 2015.
That suggests that the immunity people get from the vaccine wears off eventually. Mumps spread in close quarters, so college students and sports teams are especially vulnerable.
"Young adults between the ages of 17 and 21 are at highest risk," Marin told the ACIP meeting.
She said the CDC is still studying whether using the vaccine can control outbreaks.
ACIP makes recommendations to the CDC. If the CDC follows Wednesday's votes, it will recommend giving a third dose of MMR to the affected groups in outbreaks. It could also update its advice by recommending the new shingles vaccine, Shingrix, for adults over 50 and suggest they get Shingrix instead of Zostavax, and even if they have already been vaccinated with Zostavax.
Shingles can be extremely painful and debilitating. Anyone who has had chickenpox is vulnerable to getting it — the herpes zoster virus causes both shingles and chickenpox.
About a million people a year get shingles in the U.S. and it can cause a complication called post-herpetic neuralgia — pain that lingers long after the blistering rash is gone.
And people who have already had shingles once can get the vaccine.
"The new recommendations mean up to 62 million more adults in the US should be immunized, approximately 42 million aged 50-59 years old and 20 million who have previously been vaccinated against shingles," GlaxoSmithKline, which makes the vaccine, said in a statement.