The Minnesota Department of Health (MDH) has reported that the state is currently experiencing its largest mumps outbreak since 2006.1 MDH Information Officer Doug Shultz confirmed that 41 of the 63 cases identified statewide this year have occurred in a cluster at the University of Minnesota (UMN) Twin Cities campus, where 39 of the 41 infected students had been fully vaccinated for mumps. UMN requires MMR (measles, mumps, rubella) vaccination.
This mumps outbreak at UMN parallels other mumps outbreaks on college campuses across the country in recent months, including Harvard University and Penn State University, where all of the infected students had received at least one dose of the MMR vaccine and most had received two.2 3
According to the Centers for Disease Control and Prevention (CDC), the MMR vaccine confers full protection in 78 percent of patients who receive one dose and 88 percent of patients who receive two doses.4 Studies examining the effectiveness of the mumps component of the MMR vaccine reflect that the official CDC assessment of MMR protection may be overly optimistic.5 6
A Canadian study in 2011 found that MMR effectiveness ranged from 49-82 percent after one dose and 66-88 percent after two doses, with accumulating evidence of waning immunity over time.7 In particular, the authors noted that field analyses of MMR protection in these ranges contradicted published clinical trial data reflecting 95 percent effectiveness after one dose.
The study’s finding is consistent with evidence disclosed in 2010 by whistleblowers Stephen Krahling and Joan Wlochowski, virologists employed by vaccine manufacturer Merck & Co. to test the efficacy of the mumps component of the MMR vaccine. Krahling and Wlochowski went on to file a lawsuit charging that Merck coerced them to employ fraudulent tactics, fabricate data and ultimately inflate the stated efficacy of the vaccine.8 9 10
Mumps is a highly contagious and usually mild illness, although serious complications can occur and are more likely when the disease is contracted during adulthood. The CDC currently recommends MMR doses for all children at 12-15 months and again at 4-6 years of age.11 The timing of waning immunity after these doses combined with the close living quarters and high risk of contagion in dormitory settings may contribute to the frequency of mumps outbreaks on college campuses and the increasing incidence of complications more rare among childhood cases.12
Mumps transmission can be contained by quarantining infected people, covering the nose and mouth when coughing or sneezing, not sharing drinks or utensils, and frequently washing hands and disinfecting surfaces.13
1 Minnesota Department of Health. Mumps Disease Statistics. Health.State.mn.us.
2 Cambridge Public Health Department. 16 Confirmed Mumps Cases in Harvard Community. CambridgePublicHealth.org Mar. 24, 2016.
3 Burning S. Penn State’s mumps outbreak grows to 36 probable cases. Philly.com Mar. 3, 2017.
4 Centers for Disease Control and Prevention. Measles, Mumps, and Rubella (MMR) Vaccination: What Everyone Should Know. CDC.gov.
5 Harling R, White JM, Ramsay, ME, Macsween KF, van den Bosch C. The effectiveness of the mumps component of the MMR vaccine: a case control study. Vaccine July 1, 2005; 23(31): 4070-4074.
6 Vyse AJ, Gay NJ, Hesketh LM, Pebody R, Morgan-Capner P, Miller E. Interpreting serological surveys using mixture models: the seroepidemiology of measles, mumps and rubella in England and Wales at the beginning of the 21st century. Epidemiol Infect December 2006; 134(6): 1303–1312.
7 Deeks SL, Lim GH, Simpson Gagné L, Gubbay J, Kristjanson E, Fung C, Crowcroft NS. An assessment of mumps vaccine effectiveness by dose during an outbreak in Canada. CMAJ June 14, 2011; 183(9): 1014–1020.
8 Packel D. Antitrust, FCA Claims On Merck Mumps Vaccine To Advance. Law360 Sept. 5, 2014.
9 Stephen A. Krahling and Joan A. Wlochowski v Merck & Co., Inc. RescuePost.com.
10 Mercola J. Mumps Being Spread by and Among Vaccinated People. The Vaccine Reaction May 16, 2016.
11 CDC. Recommended Immunization Schedule forChildren and Adolescents Aged 18 Years or Younger, UNITED STATES, 2017. CDC.gov.
12 Muller S. Mumps outbreak begins affecting Iowa State. Iowa State Daily Feb. 24, 2016.
13 CDC. Mumps—Outbreak-Related Questions and Answers for Patients. CDC.gov.