Recommendation of the Advisory Committee on Immunization Practices for Use of a Third Dose of Mumps Virus–Containing Vaccine in Persons at Increased Risk for Mumps During an Outbreak

A substantial increase in the number of mumps outbreaks and outbreak-associated cases has occurred in the United States since late 2015 (1,2). To address this public health problem, the Advisory Committee on Immunization Practices (ACIP) reviewed the available evidence and determined that a third dose of measles, mumps, rubella (MMR) vaccine is safe and effective at preventing mumps. During its October 2017 meeting, ACIP recommended a third dose of a mumps virus–containing vaccine* for persons previously vaccinated with 2 doses who are identified by public health authorities as being part of a group or population at increased risk for acquiring mumps because of an outbreak. The purpose of the recommendation is to improve protection of persons in outbreak settings against mumps disease and mumps-related complications. This recommendation supplements the existing ACIP recommendations for mumps vaccination (3). In 1977, ACIP recommended 1 dose of mumps vaccine for all children aged ≥12 months (4). In response to multiple measles outbreaks in the late 1980s, in 1989 ACIP recommended routine administration of 2 doses of MMR vaccine for children, with the first dose administered at ages 12 through 15 months and the second at ages 4 through 6 years (5). In addition to improved measles control, this policy led to substantial reduction in the number of mumps cases in the United States during the 1990s, which was sustained through 2005 (3). However, in 2006, mumps outbreaks primarily affecting populations with high coverage with 2 doses of MMR vaccine in midwestern states and colleges resulted in 6,584 reported mumps cases that year (6). These outbreaks prompted ACIP to formally recommend a routine 2-dose mumps vaccination policy for school-aged children (i.e., kindergarten–grade 12) and adults at high risk (i.e., students at post-high school educational institutions, health care personnel, and international travelers) in 2006 (7). In addition, ACIP recommended that a second dose of mumps vaccine should be considered in outbreak settings for children aged 1–4 years and adults who have received 1 dose of vaccine, depending on the epidemiology of the outbreak (e.g., the age groups affected or institutions involved). Despite this recommendation, mumps outbreaks continued to be reported throughout the United States, particularly in settings where persons have close, prolonged contact (e.g., universities and close-knit communities). To assist state and local health departments in responding to mumps outbreaks, CDC issued guidance on use of a third dose of MMR vaccine in the 2012 Manual for the Surveillance of Vaccine-Preventable Diseases.† The guidance was based on limited data and provided criteria for health departments regarding when to consider use of a third dose in specifically identified target populations. Additional evidence on effectiveness and safety of the third dose of MMR vaccine recently became available and was presented to ACIP during 2017. This report summarizes the evidence considered by ACIP regarding use of a third dose of a mumps virus–containing vaccine during outbreaks and provides the recommendation for its use among persons who are at increased risk for acquiring mumps because of an outbreak.