Health Departments' Experience With Mumps Outbreak Response and Use of a Third Dose of Measles, Mumps, and Rubella Vaccine.

CONTEXT: During January 2016 to June 2017, US health departments (HDs) reported 150 mumps outbreaks. Most occurred among populations with high 2-dose measles, mumps, and rubella (MMR) vaccine coverage, prompting the Advisory Committee on Immunization Practices to examine the evidence for use of a third dose of MMR vaccine. OBJECTIVE: To evaluate HD experiences with mumps outbreak control and use of a third MMR dose during outbreaks. DESIGN: An online survey assessing mumps outbreak characteristics, outbreak response measures, challenges, and lessons learned from previous outbreaks was distributed to all 81 Council of State and Territorial Epidemiologists member HDs in August 2017. RESULTS: Sixty-one (75%) HDs responded; 46 (75%) had experience with ≥1 mumps outbreak(s) during January 2016 to August 2017. Twenty (43%) HDs recommended a third or outbreak MMR dose during mumps outbreaks; of these, 19 completed the section on use of a third dose and 8 (40%) rated the intervention "somewhat effective" or better. Health departments that used a third/outbreak dose suggested implementing the recommendation early and to a targeted group. Forty-three (73%) HDs reported having a policy for excluding persons without presumptive immunity from outbreak settings; of these, 37 (86%) had some degree of legal authority to implement this policy. Exclusion compliance improved with the use of personalized notification letters, focus groups of excluded persons and the community, and standardized messaging. Other outbreak control measures included cohorting of exposed or susceptible persons, mobile vaccination clinics and home visits, contact monitoring via text messaging, and facilitating student isolation with meal delivery and excused class absences. CONCLUSIONS: Our study revealed heterogeneity across HDs' mumps outbreak responses but also identified common challenges that will inform future Centers for Disease Control and Prevention guidance. These results were considered in the October 2017 Advisory Committee on Immunization Practices recommendation for use of a third dose of MMR vaccine for persons at increased risk for mumps during an outbreak and in the development of Centers for Disease Control and Prevention guidance for HDs when applying the Advisory Committee on Immunization Practices recommendation.