title: Measles Outbreak Associated With Low Vaccine Effectiveness Among Adults in Pohnpei State, Federated States of Micronesia, 2014.
abstract: Background.  A measles outbreak in Pohnpei State, Federated States of Micronesia in 2014 affected many persons who had received ≥1 dose of measles-containing vaccine (MCV). A mass vaccination campaign targeted persons aged 6 months to 49 years, regardless of prior vaccination. Methods.  We evaluated vaccine effectiveness (VE) of MCV by comparing secondary attack rates among vaccinated and unvaccinated contacts after household exposure to measles. Results.  Among 318 contacts, VE for precampaign MCV was 23.1% (95% confidence interval [CI], -425 to 87.3) for 1 dose, 63.4% (95% CI, -103 to 90.6) for 2 doses, and 95.9% (95% CI, 45.0 to 100) for 3 doses. Vaccine effectiveness was 78.7% (95% CI, 10.1 to 97.7) for campaign doses received ≥5 days before rash onset in the primary case and 50.4% (95% CI, -52.1 to 87.9) for doses received 4 days before to 3 days after rash onset in the primary case. Vaccine effectiveness for most recent doses received before 2010 ranged from 51% to 57%, but it increased to 84% for second doses received in 2010 or later. Conclusions.  Low VE was a major source of measles susceptibility in this outbreak; potential reasons include historical cold chain inadequacies or waning of immunity. Vaccine effectiveness of campaign doses supports rapid implementation of vaccination campaigns in outbreak settings.
authors.affiliation: National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Craig M
authors.initials: CM
authors.lastname: Hales
authors.affiliation: Division of Primary Health Care , Pohnpei State , Federated States of Micronesia.
authors.forename: Eliaser
authors.initials: E
authors.lastname: Johnson
authors.affiliation: Department of Health and Social Affairs , Government of the Federated States of Micronesia.
authors.forename: Louisa
authors.initials: L
authors.lastname: Helgenberger
authors.affiliation: National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Papania
authors.affiliation: National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Maribeth
authors.initials: M
authors.lastname: Larzelere
authors.affiliation: Department of Health and Social Affairs , Government of the Federated States of Micronesia.
authors.forename: Sameer V
authors.initials: SV
authors.lastname: Gopalani
authors.affiliation: Center for Global Health , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Emmaculate
authors.initials: E
authors.lastname: Lebo
authors.affiliation: National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Greg
authors.initials: G
authors.lastname: Wallace
authors.affiliation: Center for Global Health , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Edna
authors.initials: E
authors.lastname: Moturi
authors.affiliation: National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Carole J
authors.initials: CJ
authors.lastname: Hickman
authors.affiliation: National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Rota
authors.affiliation: Division of Primary Health Care , Pohnpei State , Federated States of Micronesia.
authors.forename: Hinden S
authors.initials: HS
authors.lastname: Alexander
authors.affiliation: National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention , Atlanta, Georgia.
authors.forename: Mona
authors.initials: M
authors.lastname: Marin
keywords: Federated States of Micronesia; MMR; measles; measles vaccine; vaccine effectiveness