title: Measles susceptibility in young Thai men suggests need for young adult measles vaccination: a cross sectional study.
abstract: BACKGROUND
  Measles remains a major public health concern in Thailand despite the introduction of vaccination since 1984. Similar to other countries, Thailand has experienced numerous measles outbreaks including adult communities such as university student dormitories, prisons, refugee camps, and military recruit camps. These outbreaks raise questions on the seroprotective antibody level in Thai adults.
  
  
  METHODS
  To better understand measles susceptibility in young Thai adults, a retrospective measles seroprevalence study on repository serum specimens obtained with informed consent from young Thai men entering the Royal Thai Army (RTA) during 2007-2008 was conducted. A total of 7760 stratified randomized samples were chosen by residence province. Measles IgG titer was measured using a commercial IgG quantitative ELISA kit following the manufacturer's instructions. An antibody level ≥ 250 International Units per Liter (IU/L) was interpreted as seropositive.
  
  
  RESULTS
  The overall measles seroprevalence was 78.5 % (95 % Confidence Interval: 77.6-79.4 %) with geometric mean titer of 738 IU/L (95 % Confidence Interval: 716-760 IU/L). The measles seroprevalence by province ranged from 59.6 % to 93.1 %. A trend of decreasing seroprevalence in the younger cohorts despite increasing immunization coverage was found. Lower seroprevalence than vaccination coverage was observed in the youngest age group.
  
  
  CONCLUSIONS
  To achieve long term measles control and elimination, an integrated two doses vaccination strategy has been implemented in children in Thailand. This nationwide measles seroprevalence study in young adult RTA recruits found a measles seroprevalence lower than WHO's recommendation for measles outbreak prevention and elimination. These results raise concerns for measles control in Thailand. Supplementary immunization in young adults is essential especially in high-risk and densely populated communities to establish herd immunity for outbreak prevention and elimination.
authors.affiliation: Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand. siriphang@afrims.org.
authors.forename: Siriphan
authors.initials: S
authors.lastname: Gonwong
authors.affiliation: Division of Research, Armed Forces Research Institute of Medical Sciences, Bangkok, 315/6 Rajvithi Road, Bangkok, 10400, Thailand.
authors.forename: Thippawan
authors.initials: T
authors.lastname: Chuenchitra
authors.affiliation: Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand.
authors.forename: Patchariya
authors.initials: P
authors.lastname: Khantapura
authors.affiliation: Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand.
authors.forename: Dilara
authors.initials: D
authors.lastname: Islam
authors.affiliation: Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Mason
mesh_terms: D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks / Q000517:prevention & control*; D004198:Disease Susceptibility; D006301:Health Services Needs and Demand; D006801:Humans; D008297:Male; D008457:Measles / Q000453:epidemiology* / Q000517:prevention & control*; D008458:Measles Vaccine / Q000008:administration & dosage*; D008889:Military Personnel / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012306:Risk; D016036:Seroepidemiologic Studies; D013785:Thailand / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D008458:Measles Vaccine
keywords: Disease susceptibility; Measles; Seroprevalence; Thailand; Vaccination; Young adult