title: Comparative long term immunogenicity of two recombinant hepatitis B vaccines and the effect of a booster dose given after five years in a low endemicity country.
abstract: BACKGROUND
  Few data are available concerning the long term immunogenicity of the pediatric doses of hepatitis B vaccines given to preteenagers. The long term effect of the booster dose in teenagers is unknown. We evaluated the immunogenicity of 2 pediatric hepatitis vaccines after primary vaccination and after a booster dose.
  
  
  METHODS
  A prospective 15-year follow-up study of the immunogenicity of 2 hepatitis B vaccines was initiated in 1995 in Quebec City, Canada. One year apart, 1129 children 8-10 years old received Engerix-B 10 microg (EB), and 1126 received Recombivax-HB 2.5 microg (RB) vaccine after a 0-, 1-, 6-month schedule. After 5 years, one-third of the 2 cohorts were randomly selected. A booster dose of EB 10 microg or RB 5 microg was administered according to the vaccine used in the primary immunization. Antibodies were measured before, 1 month after and 1 year after the booster injection.
  
  
  RESULTS
  Before the booster dose, anti-HB surface antibody (HBs) was detected in 94.7% of the EB subjects and in 95.2% of the RB subjects (P = 0.85). The geometric mean titer (GMT) was higher in the EB than in the RB group (252 mIU/mL versus 66 mIU/mL, P < 0.0001). One month after the booster, 99.7% of subjects in the EB group and 99.6% in the RB group had a detectable anti-HBs, and 99.0 and 99.3%, respectively, had anti-HBs > or =10 mIU/mL. The anti-HBs GMT was 113,201 mIU/mL in the EB and 16,623 mIU/mL in the RB groups (P < 0.0001). One year after the booster, 99.3% of subjects in the EB group and 100% in the RB group had detectable anti-HBs, and 97.9 and 98.5% respectively, had anti-HBs > or =10 mIU/mL. The anti-HBs GMT was 14,028 mIU/mL in the EB and 3437 mIU/mL in the RB group (P < 0.0001).
  
  
  CONCLUSIONS
  The immunity persists for at least 5 years after the primary vaccination with both pediatric vaccines in 99% of children vaccinated at the age of 8-10 years. It confirms that no booster is needed at that point.
authors.affiliation: Institut National de Santé Publique du Québec, Québec, Canada. bernard.duval@ssss.gouv.qc.ca
authors.forename: Bernard
authors.initials: B
authors.lastname: Duval
authors.forename: Vladimir
authors.initials: V
authors.lastname: Gîlca
authors.forename: Nicole
authors.initials: N
authors.lastname: Boulianne
authors.forename: Philippe
authors.initials: P
authors.lastname: De Wals
authors.forename: Richard
authors.initials: R
authors.lastname: Massé
authors.forename: Gisele
authors.initials: G
authors.lastname: Trudeau
authors.forename: Gaston
authors.initials: G
authors.lastname: De Serres
mesh_terms: D000704:Analysis of Variance; D002648:Child; D015331:Cohort Studies; D019353:Endemic Diseases; D005260:Female; D005500:Follow-Up Studies; D006509:Hepatitis B / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control*; D006510:Hepatitis B Antibodies / Q000032:analysis / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage*; D006801:Humans; D007109:Immunity / Q000502:physiology*; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007156:Immunologic Memory; D015994:Incidence; D008297:Male; D015999:Multivariate Analysis; D011446:Prospective Studies; D011792:Quebec / Q000453:epidemiology; D018570:Risk Assessment; D013997:Time Factors; D014611:Vaccination / Q000592:standards / Q000639:trends; D014614:Vaccines, Synthetic / Q000008:administration & dosage*
chemical_list: C075654:Engerix-B; D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines; D014614:Vaccines, Synthetic