title: Prevalence of chronic hepatitis B virus infection before and after implementation of a hepatitis B vaccination program among children in Nepal.
abstract: BACKGROUND
  In Nepal, an estimated 2-4% of the population has chronic hepatitis B virus (HBV) infection. To combat this problem, from 2002 to 2004, a national three dose hepatitis B vaccination program was implemented to decrease infection rates among children. The program does not currently include a birth dose to prevent perinatal HBV transmission. In 2012, to assess the impact of the program, we conducted a serosurvey among children born before and after vaccine introduction.
  
  
  METHODS
  In 2012, a cross-sectional nationally representative stratified cluster survey was conducted to estimate hepatitis B surface antigen (HBsAg) prevalence among children born from 2006 to 2007 (post-vaccine cohort) and among children born from 2000 to 2002 (pre-vaccine cohort). Demographic data, as well as written and oral vaccination history were collected. All children were tested for HBsAg; mothers of HBsAg positive children were also tested. Furthermore, we evaluated the field sensitivity and specificity of the SD Bioline HBsAg rapid diagnostic test by comparing results with an enzyme immunoassay.
  
  
  RESULTS
  Among 2181 post-vaccination cohort children with vaccination data by either card or recall, 86% (95% confidence interval [CI] 77-95%) received ≥ 3 hepatitis B vaccine doses. Of 1200 children born in the pre-vaccination cohort, 0.28% (95% CI 0.09-0.85%) were positive for HBsAg; of 2187 children born in the post-vaccination cohort, 0.13% (95% CI 0.04-0.39%) were positive for HBsAg (p=0.39). Of the six children who tested positive for HBsAg, two had mothers who were positive for HBsAg. Finally, we found the SD Bioline HBsAg rapid diagnostic test to have a sensitivity of 100% and a specificity of 100%.
  
  
  CONCLUSIONS
  This is the first nationally representative hepatitis B serosurvey conducted in Nepal. Overall, a low burden of chronic HBV infection was found in children born in both the pre and post-vaccination cohorts. Current vaccination strategies should be continued.
authors.affiliation: Child Health Division, Department of Health Services, Ministry of Health and Population, Kathmandu, Nepal. Electronic address: drshyam@hotmail.com.
authors.forename: Shyam Raj
authors.initials: SR
authors.lastname: Upreti
authors.affiliation: Expanded Programme on Immunization, World Health Organization, PO Box 108, United Nations House, Kathmandu, Nepal. Electronic address: gurungs@searo.who.int.
authors.forename: Santosh
authors.initials: S
authors.lastname: Gurung
authors.affiliation: Global Immunization Division, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30329, United States. Electronic address: hgo9@cdc.gov.
authors.forename: Minal
authors.initials: M
authors.lastname: Patel
authors.affiliation: Center for Molecular Dynamics Nepal, GPO Box 21409, Kathmandu, Nepal. Electronic address: s.dixit@cmdn.org.
authors.forename: Sameer M
authors.initials: SM
authors.lastname: Dixit
authors.affiliation: Expanded Programme on Immunization, World Health Organization, PO Box 108, United Nations House, Kathmandu, Nepal. Electronic address: kendallkrause@gmail.com.
authors.forename: L Kendall
authors.initials: LK
authors.lastname: Krause
authors.affiliation: National Public Health Laboratory, Department of Health Services, Ministry of Health and Population, Kathmandu, Nepal. Electronic address: geeta.nphl@gmail.com.
authors.forename: Geeta
authors.initials: G
authors.lastname: Shakya
authors.affiliation: Global Immunization Division, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30329, United States. Electronic address: kpw9@cdc.gov.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Wannemuehler
authors.affiliation: Center for Molecular Dynamics Nepal, GPO Box 21409, Kathmandu, Nepal. Electronic address: r.rajbhandari@cmdn.org.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Rajbhandari
authors.affiliation: Expanded Programme on Immunization, World Health Organization, PO Box 108, United Nations House, Kathmandu, Nepal. Electronic address: boharar@SEARO.WHO.INT.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Bohara
authors.affiliation: Expanded Programme on Immunization, World Health Organization, PO Box 108, United Nations House, Kathmandu, Nepal. Electronic address: schluterw@wpro.who.int.
authors.forename: W William
authors.initials: WW
authors.lastname: Schluter
mesh_terms: D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000097:blood*; D017325:Hepatitis B Vaccines / Q000627:therapeutic use*; D019694:Hepatitis B, Chronic / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D017589:Immunization Programs; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D009390:Nepal / Q000453:epidemiology; D011237:Predictive Value of Tests; D015995:Prevalence; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies
chemical_list: D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines
keywords: Hepatitis B virus; Nepal; Seroprevalence; Vaccine