This paper presents data from two studies that evaluated 5-y and 10-y persistence of antibodies against hepatitis B (HBV) surface antigen (anti-HBs) and immune response to an HBV vaccine challenge in children and adolescents who had received three doses of a HBV vaccine in infancy as part of routine clinical practice [NCT00519649/NCT00984139]. Anti-HBs antibody concentrations >= 10 mIU/ml persisted in 83.3% (95% confidence interval [CI]: 78.5-87.5) and 78.3% (95% CI: 73.1-83.0) of subjects aged 7-8 y and 12-13 y, respectively 5-10 y after infant vaccination. One month post-challenge dose, 98.2% (95% CI: 95.9-99.4) and 93.7% (95% CI: 90.2-96.2) of subjects in the two age groups, respectively had anti-HBs antibody concentrations >= 100 mIU/ml. Overall, 99.6% (95% CI: 98-100) and 97.2% (95% CI: 94.5-98.8) of subjects aged 7-8 y and 12-13 y mounted an anamnestic response to the HBV challenge dose, which was well-tolerated. Healthy children aged 7-8 y and adolescents aged 12-13 y received three doses of a monovalent pediatric HBV vaccine (10 mu g of HBsAg) before 18 mo of age. Serum samples collected before and one month post-HBV vaccine challenge dose were tested for anti-HBs antibody concentrations. Safety assessments were made for the HBV vaccine challenge dose. A three-dose childhood HBV immunization regimen induced persistence of antibodies against HBV infection for 10 y, up to adolescence. This vaccination regimen also conferred long-term immune memory against HBV as evidenced by the strong anamnestic response to the HBV vaccine challenge, despite waning anti-HBs antibody levels.
