title: Hepatitis B seroprevalence in Thailand: 12 years after hepatitis B vaccine integration into the national expanded programme on immunization.
abstract: OBJECTIVE
  To evaluate the impact of the universal hepatitis B (HB) vaccination programme on the prevalence of hepatitis B surface antigen (HBsAg) carriers and immunity to HB virus infection among children <18 years and to determine the HB seroprevalence in the Thai population.
  
  
  METHODS
  We enrolled people in four provinces, including Chiangrai, Udon Thani, Chonburi and Nakhon Si Thammarat to geographically represent populations in the North, Northeast, Center and South of the country respectively. Serology for HBsAg, anti-hepatitis B surface (anti-HBs), and anti-hepatitis B core (anti-HBc) was tested using ELISA commercial kits. In total, 6213 subjects aged 6 months to 60 years from the four provincial hospitals and two to three district hospitals of each participating province participated.
  
  
  RESULTS
  Overall HBsAg, anti-HBs, and anti-HBc seropositive rates amounted to 4%, 41.6% and 26.5% respectively. Of 2887 participants aged 6 months to 18 years, 2303 were born after (group I) and 584 prior to (group II) HB vaccine integration into the expanded programme on immunization of each participating province. The HBsAg seropositive rate was 0.7% among group I children and 4.3% among group II children. The prevalence rate of anti-HBc was 2.9% in group I and 15.8% in group II. In children under 18 years, the HBsAg carrier rate was 0.98% among complete vaccinees and 1.36% among participants without vaccination.
  
  
  CONCLUSIONS
  This finding supports the efficacy of universal HB immunization in reducing the prevalence of HB infection in Thailand which is a highly endemic country.
authors.affiliation: Center of Excellence in Viral Hepatitis Research, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Voranush
authors.initials: V
authors.lastname: Chongsrisawat
authors.forename: Pornsak
authors.initials: P
authors.lastname: Yoocharoen
authors.forename: Apiradee
authors.initials: A
authors.lastname: Theamboonlers
authors.forename: Piyanit
authors.initials: P
authors.lastname: Tharmaphornpilas
authors.forename: Porpit
authors.initials: P
authors.lastname: Warinsathien
authors.forename: Supakarn
authors.initials: S
authors.lastname: Sinlaparatsamee
authors.forename: Siriraj
authors.initials: S
authors.lastname: Paupunwatana
authors.forename: Kasemporn
authors.initials: K
authors.lastname: Chaiear
authors.forename: Sawan
authors.initials: S
authors.lastname: Khwanjaipanich
authors.forename: Yong
authors.initials: Y
authors.lastname: Poovorawan
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002353:Carrier State; D002648:Child; D002675:Child, Preschool; D006509:Hepatitis B / Q000453:epidemiology* / Q000276:immunology; D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens / Q000097:blood; D017325:Hepatitis B Vaccines / Q000627:therapeutic use*; D006801:Humans; D007110:Immunity, Active / Q000276:immunology; D017589:Immunization Programs / Q000458:organization & administration*; D007223:Infant; D008875:Middle Aged; D016036:Seroepidemiologic Studies; D013785:Thailand / Q000453:epidemiology
chemical_list: D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines