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Mumps outbreaks linked to waning vaccine protection, study says

The MMR vaccine, given in two doses to children, protects against the measles, mumps and rubella. Yet the United Stat...

Posted: Mar 21, 2018 8:44 PM
Updated: Mar 21, 2018 8:44 PM

The MMR vaccine, given in two doses to children, protects against the measles, mumps and rubella. Yet the United States and Europe have seen more than a few outbreaks of mumps, a contagious viral disease, in the past couple of years.

This resurgence may be due to waning protection bestowed by the mumps portion of the vaccine, according to a new study published in the journal Science Translational Medicine. A simple booster shot at age 18 could thwart future outbreaks, the Harvard researchers believe.

Up to 10% of mumps infections in teenagers or older people may cause complications

Given recommended doses of MMR vaccine, protection lasts on average 27 years

"The pattern we observed is a lot more consistent with what we would expect from a waning vaccine," said Joseph A. Lewnard, co-author of the study and a postdoctoral research fellow at Harvard's TH Chan School of Public Health. This is "a reassuring message" so far as it's a relatively simple problem to solve.

Searching for answers

Mumps, which is typically spread through saliva and mucus, causes fever, muscle aches, loss of appetite and the characteristic puffy cheeks and jaw from swollen salivary glands. In 1977, the US Centers for Disease Control and Prevention began to recommend two doses of the MMR vaccine for children.

For the new study, Lewnard and Yonatan Grad, assistant professor of immunology and infectious diseases at TH Chan, examined data from six separate mumps vaccine effectiveness studies conducted in the United States and Europe. Their goal was to understand the underlying reasons for a series of mumps outbreaks on college campuses since 2006.

These outbreaks are troubling for two reasons, Lewnard and Grad wrote.

First, up to 10% of mumps infections in teenagers or adults may cause severe complications, including deafness, meningitis and involvement of the testes or ovaries. Children who get sick with the mumps typically do not experience such severe symptoms.

Second, most recent mumps outbreaks have occurred among people who had received the recommended two vaccine doses.

The researchers wondered, is the vaccine less effective against emerging and circulating strains of the mumps virus? Or does the protection provided by the vaccine wane over time?

'Broad protection' against all strains

The new study showed the vaccine to be effective in providing "broad protection against all different strains of the mumps virus," Lewnard said. However, this protection did not last forever.

"We estimated that protection lasts on average 27 years," he said. "We estimate that about 25% of people will lose protection and be at risk for mumps in about eight years and that 50% will be at risk in about 19 years, and 75% of people will be at risk within 38 years. So the timing at which people lose protection can definitely vary individually."

In short, the mumps portion of the MMR induces a shorter-lasting immune system response than either the measles or the rubella components has shown in laboratory studies, Lewnard said.

Lewnard and Grad modeled options for when a booster shot should be administered to maximize protection and found that a booster dose around age 18 should be best, though it is unclear how long the additional protection might last.

"That's the age people are beginning to congregate," Lewnard said, whether on university campuses or in the military.

Outbreaks typically occur in congregate settings where there is crowding and close contact. In such places, saliva is transferred person to person due to coughing, sneezing, kissing and the sharing utensils, lipstick or cigarettes.

In fact, the military already has an existing policy of giving everyone an MMR dose when they come into basic training because, years ago, they had a similar problem with outbreaks, Lewnard said.

Just last year, the Advisory Committee on Immunization Practices -- a panel of medical and public health experts who meet three times a year to offer vaccination guidance to the CDC -- recommended the use of a third "booster" shot of the MMR vaccine (even for people who are up to date on the recommended doses) during mumps outbreaks.

"This is a recommendation that is on the books that people should be aware of in case they are, for instance, at a college when an outbreak is reported," Lewnard said.

Infectious disease specialist Dr. William Schaffner said the new research "reinforces what we're doing already," namely, recommending a booster shot in situations of outbreaks.

'Milder' illness with the shot

College health authorities, in collaboration with local authorities, have given that additional dose of MMR during some recent outbreaks. "When you get in early, you find out it's confined to a sorority or just a football team, and you can identify a subgroup of students and vaccinate them and stop the outbreak very early," said Schaffner, who was not involved in the new research. "It doesn't turn it off like a switch -- so it is not a be all and end all -- but it is a contribution."

Yet there's an "underappreciated" fact about the MMR vaccine: Although it is not perfect in preventing illness completely, it does a good job preventing many complications, Schaffner said. "So your illness is milder, and this has been a striking feature of the mumps outbreaks that have been studied."

Among the unanswered questions, he said, is how long protection would last if people were given a booster shot. "That's a large unknown, and that's why, at the moment, the (immunization committee) has not recommended a third dose for everybody in adolescence."

Still, mumps outbreaks have happened "all across the country" and have been "noteworthy," he said. Communities or colleges that have experienced outbreaks have devoted substantial resources to defining the extent, identifying who needs to be vaccinated, educating people and creating quarantines.

"That's why it's become so much a matter of current discussion," Schaffner said, adding that the United States does a good job of vaccinating against the mumps. In fact, nearly 92% of infants receive their first shot of the MMR in the US, and compared with the pre-vaccine era, there has been a more than 99% decrease in mumps cases, according to the CDC.

In Europe, Israel and other places, he said, vaccination rates are not quite as high, and outbreaks of mumps still occur. Travelers may bring the mumps virus with them, so US officials have been working "diplomatically" to get other countries to be thorough with vaccinations, Schaffner said.

"The more all the countries of the world use the mumps vaccine effectively, the less mumps we'll all have -- even though the vaccine is not perfect," he said.

Indiana Coronavirus Cases

Data is updated nightly.

Cases: 751242

Reported Deaths: 13795
CountyCasesDeaths
Marion1032931788
Lake556911009
Allen41692692
St. Joseph36990565
Hamilton36588417
Elkhart29398461
Tippecanoe22901226
Vanderburgh22556400
Porter19356325
Johnson18471389
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Clark13226195
Madison13149344
Vigo12614253
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Monroe12207176
Delaware10966198
Howard10321225
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Hancock8576146
Bartholomew8169157
Warrick7860156
Floyd7811180
Grant7242179
Wayne7162201
Boone6966103
Morgan6761141
Dubois6218118
Marshall6209116
Cass6016110
Henry5900110
Dearborn589878
Noble581488
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Shelby501496
Lawrence4742122
Gibson444894
Clinton442355
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DeKalb439885
Montgomery438090
Whitley406543
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Steuben400159
Miami395269
Jasper388054
Knox375991
Putnam372960
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White331953
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Greene286885
Fayette284864
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Scott270156
Clay267148
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Blackford136232
Pulaski120647
Newton113936
Brown104243
Crawford102516
Benton101714
Martin91715
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Switzerland8148
Union72810
Ohio57911
Unassigned0420

Ohio Coronavirus Cases

Data is updated nightly.

Cases: 1108736

Reported Deaths: 20166
CountyCasesDeaths
Franklin1287201467
Cuyahoga1157922211
Hamilton813971250
Montgomery525481043
Summit484271001
Lucas43353820
Butler39013606
Stark33332929
Lorain25672505
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Mahoning22370603
Lake21207388
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Delaware18852136
Licking16662222
Fairfield16574204
Trumbull16548482
Medina15610271
Greene15281248
Clark14237306
Wood13292200
Portage13251215
Allen11913239
Richland11605211
Miami10849225
Wayne9141223
Columbiana9032230
Muskingum8906135
Pickaway8663122
Tuscarawas8649250
Marion8642138
Erie8056165
Ashtabula7160179
Hancock6998132
Ross6944161
Geauga6838151
Scioto6534106
Belmont6157174
Union584549
Lawrence5731102
Jefferson5678158
Huron5546122
Sandusky5442126
Darke5420129
Seneca5348128
Washington5319109
Athens523960
Auglaize502187
Mercer487385
Shelby476895
Knox4571112
Madison444266
Ashland435797
Putnam4336103
Defiance432399
Fulton432074
Crawford4037110
Brown402461
Logan387677
Preble3855105
Clinton379166
Ottawa373681
Highland359665
Williams348278
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Guernsey324953
Jackson318254
Perry297350
Morrow291840
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Hardin275265
Henry273467
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Coshocton269060
Van Wert247264
Adams243256
Pike242835
Gallia240650
Wyandot234556
Hocking220563
Carroll197348
Paulding176542
Meigs148440
Monroe136344
Noble136239
Harrison114138
Morgan109624
Vinton85517
Unassigned03
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