title: Long-term protection against carriage of hepatitis B virus after infant vaccination.
abstract: BACKGROUND
  Carriage of hepatitis B virus (HBV) is a major risk factor for liver cirrhosis and hepatocellular carcinoma. Infant vaccination has been effective in preventing horizontal transmission during early childhood. It is unknown whether protection is maintained into early adulthood.
  
  
  METHODS
  In 1984, early childhood vaccination was introduced in 2 rural Gambian villages. In 2003, serological assessment of 81.5% of 1,350 eligible participants 1-24 years old was done, to determine vaccine efficacy against infection and carriage.
  
  
  RESULTS
  Overall vaccine efficacy against infection and carriage was 83.4% (95% confidence interval [CI], 79.8%-86.6%) and 96.5% (85% CI, 93.9%-98.9%), respectively. Vaccine efficacy against infection was similar when restricted to primary responders (85.3%), but a significant effect of peak antibody concentration was found. Both vaccine efficacy and levels of hepatitis B surface antibody (anti-HBs) decreased with age, resulting in a vaccine efficacy against infection and carriage among 20-24-year-old participants of 70.9% (95% CI, 60.4%-80.5%) and 91.1% (95% CI, 75.8%-100%), respectively. Fifteen years after vaccination, fewer than half of the vaccinees had detectable anti-HBs. The prevalence of carriage in the unvaccinated population was similar to the prevalence 20 years earlier.
  
  
  CONCLUSIONS
  HBV vaccination early during life can provide long-lasting protection against carriage, despite decreasing antibody levels. The role played by subclinical boosting and the necessity of a booster need to be evaluated.
authors.affiliation: Medical Research Council, Fajara, The Gambia. marianne.van.der.sande@rivm.nl
authors.forename: M A B
authors.initials: MA
authors.lastname: van der Sande
authors.forename: P
authors.initials: P
authors.lastname: Waight
authors.forename: M
authors.initials: M
authors.lastname: Mendy
authors.forename: P
authors.initials: P
authors.lastname: Rayco-Solon
authors.forename: P
authors.initials: P
authors.lastname: Hutt
authors.forename: T
authors.initials: T
authors.lastname: Fulford
authors.forename: C
authors.initials: C
authors.lastname: Doherty
authors.forename: S J
authors.initials: SJ
authors.lastname: McConkey
authors.forename: D
authors.initials: D
authors.lastname: Jeffries
authors.forename: A J
authors.initials: AJ
authors.lastname: Hall
authors.forename: H C
authors.initials: HC
authors.lastname: Whittle
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002353:Carrier State / Q000517:prevention & control*; D002648:Child; D002675:Child, Preschool; D005714:Gambia; D006509:Hepatitis B / Q000517:prevention & control*; D006510:Hepatitis B Antibodies / Q000097:blood; D006514:Hepatitis B Surface Antigens / Q000097:blood; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000276:immunology*; D006801:Humans; D007223:Infant
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines