Risk Factors for Measles Virus Infection Among Adults During a Large Outbreak in Postelimination Era in Mongolia, 2015

J Infect Dis. 2017 Dec 5;216(10):1187-1195. doi: 10.1093/infdis/jix449.


Background: In 2015, a large nationwide measles outbreak occurred in Mongolia, with very high incidence in the capital city of Ulaanbaatar and among young adults.

Methods: We conducted an outbreak investigation including a matched case-control study of risk factors for laboratory-confirmed measles among young adults living in Ulaanbaatar. Young adults with laboratory-confirmed measles, living in the capital city of Ulaanbaatar, were matched with 2-3 neighborhood controls. Conditional logistic regression was used to estimate adjusted matched odds ratios (aMORs) for risk factors, with 95% confidence intervals.

Results: During March 1-September 30, 2015, 20 077 suspected measles cases were reported; 14 010 cases were confirmed. Independent risk factors for measles included being unvaccinated (adjusted matched odds ratio [aMOR] 2.0, P < .01), being a high school graduate without college education (aMOR 2.6, P < .01), remaining in Ulaanbaatar during the outbreak (aMOR 2.5, P < .01), exposure to an inpatient healthcare facility (aMOR 4.5 P < .01), and being born outside of Ulaanbaatar (aMOR 1.8, P = .02).

Conclusions: This large, nationwide outbreak shortly after verification of elimination had high incidence among young adults, particularly those born outside the national capital. In addition, findings indicated that nosocomial transmission within health facilities helped amplify the outbreak.

Keywords: case-control; disease outbreak; measles; nosocomial infection.

Publication types

  • Historical Article
  • Research Support, U.S. Gov't, P.H.S.
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Disease Outbreaks*
  • Female
  • History, 21st Century
  • Humans
  • Incidence
  • Infant
  • Infant, Newborn
  • Male
  • Measles / epidemiology*
  • Measles / history
  • Measles / prevention & control
  • Measles / virology
  • Measles Vaccine / immunology
  • Measles virus / immunology*
  • Mongolia / epidemiology
  • Odds Ratio
  • Population Surveillance
  • Risk Factors
  • Seasons
  • Vaccination / statistics & numerical data
  • Young Adult


  • Measles Vaccine