Is Waning Immunity Causing Mumps Resurgence?

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April 26, 2018


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Thanks to the Measles, Mumps, and Rubella (MMR) vaccination, cases of the viral disease mumps had become rare occurrences since the late 1960s. But there seems to be a resurgence across the U.S. and other parts of the world which is being blamed mostly on the waning of vaccine-induced immunity in adults.

Reduced immunity to the mumps has not alarmed public health officials, at least not yet. But a recent study has put a focus on the strength of childhood vaccinations over the years. A new analysis from Harvard’s T.H. Chan School of Public Health found that vaccine-derived immune protection against mumps persists an average of about 27 years after the last dose.

These findings suggest that, in addition to the currently recommended two doses of mumps vaccine in childhood, a third dose at age 18 or booster shots later in adulthood may help sustain protection among adults. Mumps is a contagious disease caused by a virus. It typically starts with a few days of fever, headache, muscle aches, tiredness, and loss of appetite, followed by swollen salivary glands.

Even though the vaccine has drastically reduced mumps cases, outbreaks continue to occur. These outbreaks have most commonly happened in places where people have had prolonged, close contact with a person who has mumps, such as attending the same class, playing on the same sports team, or living in the same college dormitory.

The MMR immunity test is a blood analysis which provides measurements for the antibodies for measles, mumps, and rubella. This test is used to determine if a person has protective antibodies to several infectious diseases.

Most people in the United States receive MMR vaccinations when they are young. However, the immunity provided by vaccinations may not last throughout a person’s life. An MMR antibodies screening can help a person determine if they are still immune or may need a booster.

Recent mumps outbreaks, including on college campuses, began occurring among vaccinated young adults around 2006 and have continued. The resurgence is troubling to the Harvard researchers because mumps infections may cause complications, such as testicular inflammation (which may result in infertility), meningitis, and deafness, according to the U.S. Centers for Disease Control and Prevention (CDC).

Since cases have mainly occurred in vaccinated populations, the mumps resurgence has fueled questions about what’s precisely to blame — either waning immune protection from the vaccine or new strains of the mumps that evade vaccine-driven protection.

In the new study, Harvard researchers analyzed data from six epidemiological studies that tracked the effectiveness of the mumps vaccine over the past four decades in the U.S. and Europe. The researchers estimated that 25 percent of people in the U.S. vaccinated against mumps may lose protection within 7.9 years, 50 percent within 19 years, and 75 percent within 38 years.

The study will help “frame the research and policy questions on how best to control mumps,” said Yonatan Grad, assistant professor of immunology and infectious diseases at Harvard’s T.H. Chan School, who co-authored the study with Joseph Lewnard, postdoctoral research fellow at Harvard’s Center for Communicable Disease Dynamics.

”Knowing that protection wanes in the long term can help inform how we deploy vaccines to prevent or contain future outbreaks,” said Mr. Lewnard

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