Article

Epidemiology of a Mumps Outbreak in a Highly Vaccinated Island Population and Use of a Third Dose of Measles-Mumps-Rubella Vaccine for Outbreak Control- Guam 2009-2010.

1.National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC), Atlanta, GA 2.Epidemic Intelligence Service, CDC, Atlanta, GA 3.Guam Department of Public Health and Social Services, Guam, USA 4.Guam Memorial Hospital, Guam, USA 5.Guam Department of Education, Guam, USA 6.Division of Global Migration and Quarantine, CDC, Atlanta, GA 7.Office of Surveillance, Epidemiology, and Laboratory Services, CDC, Atlanta, GA.
The Pediatric Infectious Disease Journal (Impact Factor: 3.14). 10/2012; 32(4). DOI: 10.1097/INF.0b013e318279f593
Source: PubMed

ABSTRACT BACKGROUND:: Despite high two-dose measles-mumps-rubella (MMR) vaccine coverage, a large mumps outbreak occurred on the U.S. Territory of Guam during 2009-2010, primarily in school-aged children. METHODS:: We implemented active surveillance in April 2010 during the outbreak peak and characterized the outbreak epidemiology. We administered third doses of MMR vaccine to eligible students aged 9-14 years in 7 schools with the highest attack rates (ARs) between 5/18/2010-5/21/2010. Baseline surveys, follow-up surveys, and case-reports were used to determine mumps vaccine ARs. Adverse events post-vaccination were monitored. RESULTS:: Between 12/1/2009-12/31/2010, 505 mumps cases were reported. Self-reported Pohnpeians and Chuukese had the highest relative risks (54.7 and 19.7, respectively) and highest crowding indices (mean: 3.1 and 3.0 persons/bedroom, respectively). Among 287 (57%) school-aged case-patients, 270 (93%) had ≥2 MMR doses. A third MMR dose was administered to 1068 (33%) eligible students. Three-dose vaccinated students had an AR of 0.9/1000 compared with 2.4/1000 among students vaccinated with ≤2 doses more than1 incubation period pos-intervention, but the difference was not significant (p= 0.67). No serious adverse events were reported. CONCLUSIONS:: This mumps outbreak occurred in a highly vaccinated population. The highest ARs occurred in ethnic minority populations with the highest household crowding indices. After the third dose MMR intervention in highly affected schools, three-dose recipients had an AR 60% lower than students with ≤2 doses, but the difference was not statistically significant and the intervention occurred after the outbreak peaked. This outbreak may have persisted due to crowding at home and high student contact rates.

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