Mumps Outbreaks

Pre-Vaccine Era Mumps Outbreaks

In the pre-vaccine era, mumps was a common childhood disease that could cause orchitis, meningitis, pancreatitis, deafness, and even death.

There were about 212,000 cases a year in the early 1960s, before the first mumps vaccine was licensed in 1968.

Post-Vaccine Era Mumps Outbreaks

As with other vaccine-preventable diseases, there was a big drop in cases of mumps once the mumps vaccine was introduced.

In 1968, there were just over 152,000 cases and 25 deaths  and just ten years later, in 1978, that was down to 16,817 cases and 3 deaths.

Once the recommendation for the second dose of MMR came in 1990, it looked like mumps was on it’s way out.

We went from 5,292 cases and one death that year, to just 906 cases and no deaths in 1995. When measles hit its low point of 37 cases in 2004, there were just 258 cases of mumps.

That wasn’t the end for mumps though, as we had some up and down years, including big outbreaks in:

• 2006 – 6,584 cases among Midwest college students and one death
• 2008 – only 454 cases, but one death
• 2009 – 1,991 cases and two deaths
• 2010 – 2,612 cases mostly among Orthodox Jewish communities and two deaths
• 2011 – 370 cases
• 2012 – 229 cases
• 2013 – 584 cases
• 2014 – 1,223 cases involving a large outbreak in Ohio and in the NHL
• 2015 – 1,057 cases mostly among university students in Iowa and Illinois
• 2016 – 6,369 cases in 46 states (no cases in Delaware, Louisiana, Vermont, or Wyoming), with the most cases in Arkansas, Iowa, Indiana, Illinois, Maine, New York, Oklahoma, and Texas.
• 2017 – at least 6,109 cases of mumps, with cases in all states except Wyoming, South Carolina, and South Dakota. With outbreaks at Syracuse University, in Anchorage, Alaska (many unvaccinated cases), and Hawaii.
• 2018 – about 2,251 cases

Could this all be because of waning immunity?

The herd immunity threshold may need to be higher than the previously suggested 88%–92% to prevent community transmission and outbreaks of mumps.

Quinlisk on Mumps Control Today

Many of these outbreaks occur despite many of the cases having had two doses of the MMR vaccine. A third dose is sometimes recommended during these outbreaks.

That doesn’t mean that the MMR vaccine doesn’t work. After all, just compare today’s rates of mumps, even if they are a little higher than we would like, to pre-vaccine levels…

And in the biggest outbreak, in Arkansas, only 71% of people were up-to-date on their vaccines!

Of course, getting two doses of the MMR vaccine is still the best way to avoid mumps.

There is no general recommendations to get an extra shot, although a third dose of MMR during an outbreak was recently recommended by the ACIP. The recommendation has not yet been formally approved though.

A recent study that was published in the New England Journal of Medicine, Effectiveness of a Third Dose of MMR Vaccine for Mumps Outbreak Control, found a lower risk of mumps in those who got a third dose of MMR.

Not surprisingly, the study also found a much higher risk of mumps, with the highest attack rates, in those who were unvaccinated or who had just one dose!

Keep in mind that the MMR vaccine isn’t just for kids. Adults who didn’t have mumps when they were kids (or who were born before 1957, when most kids got mumps), should make sure they are vaccinated (at least one dose) and protected too.

Vaccines work. They just aren’t perfect…

And these outbreaks show that they are definitely still necessary. In the latest outbreak in Hawaii, where “has been confirmed in children and adults, both vaccinated and unvaccinated,” there have been at least “16 reports of complications due to mumps infection,” including orchitis and hearing loss.

What to Know About Mumps Outbreaks

Although mumps outbreaks are occurring among those who are vaccinated, you still have a much higher chance of getting mumps if you are unvaccinated and unprotected.

For More Information on Mumps Outbreaks:

• CDC – Mumps (Pinkbook)
• CDC – Mumps Cases and Outbreaks
• CDC – Outbreak-Related Questions and Answers for Patients
• AAP – ACIP: Give 3rd mumps vaccine dose during outbreaks
• Why Do So Many Vaccinated People Get the Mumps During an Outbreak?
• Syracuse University mumps outbreak – bad anti-vaccine math
• The 2014 Ohio Mumps Outbreak
• CDC – Mumps Outbreak at a University and Recommendation for a Third Dose of Measles-Mumps-Rubella Vaccine — Illinois, 2015–2016
• CDC – Notes from the Field: Complications of Mumps During a University Outbreak Among Students Who Had Received 2 Doses of Measles-Mumps-Rubella Vaccine — Iowa, July 2015–May 2016
• Update on Mumps Outbreak: Arkansas
• Social Media, Math And The Mystery Of A Mumps Outbreak
• Early reports show mumps on the rise in 2016, including on campuses
• Harvard has a mumps outbreak. Here’s why the virus can have a field day on campus.
• NHL Mumps Outbreak : What’s Up With The Vaccine?
• Harvard mumps outbreak – not an indictment of vaccines
• How social media and a mumps outbreak teach us that vaccines build herd immunity
• Study – Effectiveness of a Third Dose of MMR Vaccine for Mumps Outbreak Control
• Study – Mumps Control Today

Updated on January 9, 2019