title: 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 to 2010.
abstract: BACKGROUND
  Despite high 2-dose measles-mumps-rubella (MMR) vaccine coverage, a large mumps outbreak occurred on the US Territory of Guam during 2009 to 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 May 18, 2010, and May 21, 2010. Baseline surveys, follow-up surveys and case-reports were used to determine mumps ARs. Adverse events postvaccination were monitored.
  
  
  RESULTS
  Between December 1, 2009, and December 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 >1 incubation period postintervention, 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, 3-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.
authors.affiliation: National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: George E
authors.initials: GE
authors.lastname: Nelson
authors.forename: Annette
authors.initials: A
authors.lastname: Aguon
authors.forename: Engracia
authors.initials: E
authors.lastname: Valencia
authors.forename: Rita
authors.initials: R
authors.lastname: Oliva
authors.forename: Michele Leon
authors.initials: ML
authors.lastname: Guerrero
authors.forename: Richard
authors.initials: R
authors.lastname: Reyes
authors.forename: Anna
authors.initials: A
authors.lastname: Lizama
authors.forename: Daryl
authors.initials: D
authors.lastname: Diras
authors.forename: Annakutty
authors.initials: A
authors.lastname: Mathew
authors.forename: E Jessica
authors.initials: EJ
authors.lastname: Camacho
authors.forename: Moryne-Nicole
authors.initials: MN
authors.lastname: Monforte
authors.forename: Tai-Ho
authors.initials: TH
authors.lastname: Chen
authors.forename: Abdirahman
authors.initials: A
authors.lastname: Mahamud
authors.forename: Preeta K
authors.initials: PK
authors.lastname: Kutty
authors.forename: Carole
authors.initials: C
authors.lastname: Hickman
authors.forename: William J
authors.initials: WJ
authors.lastname: Bellini
authors.forename: Jane F
authors.initials: JF
authors.lastname: Seward
authors.forename: Kathleen
authors.initials: K
authors.lastname: Gallagher
authors.forename: Amy Parker
authors.initials: AP
authors.lastname: Fiebelkorn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003441:Crowding; D004196:Disease Outbreaks; D005006:Ethnicity; D005260:Female; D006141:Guam / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology*; D008875:Middle Aged; D009107:Mumps / Q000453:epidemiology* / Q000517:prevention & control*; D012959:Socioeconomic Factors; D055815:Young Adult
chemical_list: D022542:Measles-Mumps-Rubella Vaccine