MedicalResearch.com Interview with:
Cristina V. Cardemil, M.D., M.P.H.
Pediatrics, Primary Care, Public Health
Centers for Disease Control and Prevention
Atlanta, GA 30333
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The effect of a third dose of the measles–mumps–rubella (MMR) vaccine in stemming a mumps outbreak is unknown. During an outbreak among vaccinated students at the University of Iowa, health officials implemented a widespread MMR vaccine campaign. We evaluated the effectiveness of a third dose of MMR vaccine in preventing mumps cases during the outbreak, and assessed for waning immunity.
Of 20,496 university students enrolled in the 2015-16 academic year, 259 developed mumps. Prior to the outbreak, 98.1% of students had received two or more doses of MMR vaccine. During the outbreak, 4,783 students received a third dose.
The attack rate was lower among students who received a third dose of MMR vs. 2-dose recipients (6.7 vs. 14.5 per 1,000, respectively). Students had at least nine times greater risk of getting mumps if they received their second dose of MMR 13 years or more prior to the outbreak. Individuals who received a third MMR vaccine dose had a 78% lower risk for mumps than individuals who had received only two doses. This study demonstrates a lower risk of mumps in 3-dose MMR vaccine recipients, suggesting the MMR vaccine dose campaign prevented cases and may have helped stop the spread of the outbreak. Waning immunity likely contributed to the spread of the outbreak.