title: Prevalence of chronic hepatitis B virus infection after implementation of a hepatitis B vaccination program among children in three provinces in Cambodia.
abstract: BACKGROUND
  Hepatitis B virus (HBV) is highly endemic in Cambodia with an estimated pre-vaccine hepatitis B surface antigen (HBsAg) prevalence of 9%. By 2005, a hepatitis B vaccination program was implemented to decrease infection rates in children. We conducted a serosurvey to evaluate the impact of the vaccination program in 2011.
  
  
  METHODS
  A cross-sectional two-stage cluster survey was conducted to estimate HBsAg prevalence among children born from 2006 to 2007 in three provinces: Phnom Penh (urban), Kratie (rural), and Ratanakiri (remote). Demographic data, as well as written or oral vaccination history were collected. Children were tested for HBsAg. Factors associated with undervaccination and HBsAg positivity were modeled.
  
  
  RESULTS
  Coverage of timely hepatitis B vaccine birth dose (administered at ≤ 24 h) was 55% in Phnom Penh, 36% in Kratie, and 22% in Ratanakiri. Coverage with ≥ 3 hepatitis B vaccine doses (HepB3) was 91% in Phnom Penh, 82% in Kratie, and 64% in Ratanakiri. When compared with children who were born in health facilities with a skilled birth attendant (SBA), children born at home without a SBA were more likely not to have received a timely BD (adjusted relative risk [aRR]=1.94; 95% CI=1.75-2.15) as were children born at home with an SBA (aRR=1.54; 95% CI=1.32-1.80). The proportion of children who tested positive for HBsAg was 0.33% in Phnom Penh, 1.41% in Kratie, and 3.45% in Ratanakiri. In all three provinces, children who received their first dose after 7 days of life and children who never received hepatitis B vaccine had the highest HBsAg prevalence.
  
  
  CONCLUSIONS
  Progress has been made in Cambodia in decreasing the burden of chronic HBV infection among children. Improvements in vaccination coverage will further decrease the burden of disease.
authors.affiliation: University of Health Sciences, 73 Monivong Boulevard, Phnom Penh, Cambodia. maobunsoth888@yahoo.com
authors.forename: Bunsoth
authors.initials: B
authors.lastname: Mao
authors.forename: Minal K
authors.initials: MK
authors.lastname: Patel
authors.forename: Karen
authors.initials: K
authors.lastname: Hennessey
authors.forename: Richard J W
authors.initials: RJ
authors.lastname: Duncan
authors.forename: Kathleen
authors.initials: K
authors.lastname: Wannemuehler
authors.forename: Sann Chan
authors.initials: SC
authors.lastname: Soeung
mesh_terms: D002160:Cambodia / Q000453:epidemiology; D002648:Child; D003151:Community Health Centers; D003430:Cross-Sectional Studies; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000627:therapeutic use*; D006515:Hepatitis B virus / Q000276:immunology; D019694:Hepatitis B, Chronic / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D006801:Humans; D017589:Immunization Programs; D008297:Male; D012424:Rural Population; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines
keywords: 3-dose hepatitis B vaccination coverage; BD; CI; Cambodia; Confidence Interval; DE; HBV; HBsAg; HepB3; Hepatitis B virus; ICC; RR; SBA; Seroprevalence; Vaccine; WHO; World Health Organization; aRR; adjusted relative risk; design effect; hepatitis B birth dose; hepatitis B surface antigen; hepatitis B virus; intra-class correlation; relative risk; skilled birth attendant