Harvard Researchers Examine Mumps Outbreak with New Genomic Data

A team of researchers at Harvard Medical School, the Broad Institute, and the Harvard School of Public Health investigated the 2016-2017 mumps outbreak in Boston, finding previously unknown genetic connections between cases.

The researchers collaborated with the Massachusetts Department of Public Health, using genomic data and public health records to profile the behavior and transmission of the virus in an article published February 11 in PLOS Biology.

The outbreak — the largest in recent history — included more than 60 confirmed cases on Harvard’s campus. University administrators quarantined students for five days in cooperation with the Cambridge Public Health Department to stem the spread of the disease.

In total, more than 420 cases were reported in Massachusetts in 2016 and 2017 despite high rates of vaccination, baffling physicians and public health officials trying to contain the outbreak. Outside Harvard, cases were also found at 18 colleges and universities in the state, including Boston University and the University of Massachusetts Amherst.

Since 2016, mumps cases have cropped up on the Harvard campus at least three times. None of these recurrences reached the scale of the 2016 outbreak.

Co-senior author and Organismic and Evolutionary Biology professor Pardis C. Sabeti said that the researchers used high-resolution genomic data to fill in gaps from the epidemiological records collected by the University and the Massachusetts Department of Public Health.

“Genomic data is like a barcode that tells you what you’re infected with,” Sabeti said. “If you start seeing people infected by viruses with a very similar genome, it’s likely that they were all infected around the same time or from the same chain of events.”

Understanding the transmission and spread of highly contagious diseases like mumps can help contain and prevent future outbreaks. In the newly published study, the researchers discovered genetic links between cases previously classified as unrelated based on epidemiological data, connecting Harvard cases with an outbreak in East Boston.

In addition to revealing new information about the progression of the 2016 outbreak, the investigation into mumps serves as a reminder that college and university campuses are places of of high risk for transmission and infection, Sabeti said.

“You start to notice that there are certain places that become ground zero for an outbreak,” Sabeti said.

Sabeti said the mumps outbreak could be a “simulation” that could help officials contain other diseases, such as the novel coronavirus, if issues arise.

“It [mumps] is not that bad if you’ve had the vaccine, it doesn’t cause really terrible symptoms, but it allowed us to simulate what would we do in a real outbreak,” she said. “With coronavirus, it’s my hope that this one also passes and it’s not as bad as we think it is, but it’s also a great framing to say, ‘Hey, what if the coronavirus came? What would we do?’”

—Staff writer Virginia L. Ma can be reached at virginia.ma@thecrimson.com.