Mumps Outbreaks at Four Universities - Indiana, 2016.

From February to April 2016, the Indiana State Department of Health (ISDH) confirmed mumps outbreaks at four universities (three public and one private). All universities were located within 65 miles of Indianapolis; however, epidemiologic links among outbreaks were limited. ISDH and local health departments investigated the outbreaks and initiated control measures at all universities. A protocol describing recommended testing for mumps, testing priorities during the outbreak, and a preauthorization process for submitting specimens to the ISDH Laboratory (ISDHL) was developed and disseminated to providers and public health partners (1). Outbreaks at each university were declared over after two incubation periods* elapsed without identified cases; the last outbreak ended September 10, 2016. Among the 281 confirmed and probable cases identified, 216 (76.9%) persons had documentation of presumptive evidence of immunity† (2). At some universities, documentation of receipt of 2 doses of measles, mumps, rubella vaccine (MMR), which is a criterion for evidence of immunity, was not available and required substantial personnel time to verify. Implementation of policies for excluding susceptible persons from classes and other group settings was also difficult. The laboratory testing protocol increased the percentage of specimens testing positive and improved case detection. Outbreak-specific laboratory testing guidance on specimen collection for mumps confirmation and standardized vaccination documentation in highly vaccinated settings could aid outbreak management. Evaluation of exclusion policies might also be necessary. In 2018, the Advisory Committee on Immunization Practices (ACIP) published a recommendation that persons previously vaccinated with 2 doses of MMR who are determined by public health authorities to be part of a group at increased risk for infection during a mumps outbreak receive a third dose of MMR (3).