Describe the 2-dose regimen for hepatitis B vaccine for certain young adolescents.

For the 2-dose adolescent schedule, the adult dose of Recombivax HB (1.0 mL dose) is administered to adolescents age 11 through 15 years, with the second dose given 4 to 6 months after the first dose. In immunogenicity studies, antibody concentrations and end seroprotection rates (at least 10 mIU/mL of anti-HBs) were similar with the 2-dose schedule and the 3-dose schedule (0.5 mL dose). As with other HepB vaccination schedules, if administration of the 2-dose schedule is interrupted, it is not necessary to restart the series. Children and adolescents who have begun vaccination with a pediatric (0.5 mL) dose of Recombivax HB should complete the 3-dose series with this dose. If it is not clear which dose an adolescent was administered at the start of a series, the series should be completed with the 3-dose schedule. Heplisav-B, the 2-dose HepB vaccine given with a 4-week interval between doses, is licensed only for adolescents and adults beginning at age 18 years.