Long-term (5-year) antibody persistence following two- and three-dose regimens of a combined hepatitis A and B vaccine in children aged 1-11 years.

This study compared the long-term persistence of anti-hepatitis A (anti-HAV) and B (anti-HBs) antibodies, 5 years after vaccination of subjects aged 1–11 years with a combined hepatitis A and B vaccine either in a two-dose (0, 6 months, Adult formulation) or a three-dose (0, 1, 6 months, Paediatric formulation) schedule. At the end of the 5 years, all subjects (100%) in both groups continued to have anti-HAV antibodies ≥15mIU/mL, while 94–97% of subjects in both groups had anti-HBs antibody concentrations ≥10mIU/mL. Subjects with anti-HBs antibody concentration ≤10mIU/mL were administered a challenge dose of hepatitis B vaccine. All subjects mounted a vigorous immune response to the challenge indicating the presence of immunological memory to HBV.