Long-Term Immune Persistence of GSK Biologicals' Combined Hepatitis A & B Vaccine Injected According to a 0,1,6 Month Schedule

This is a long-term follow-up study at Years 11, 12, 13, 14 and 15 after primary vaccination with GSK Biologicals' hepatitis A/hepatitis B vaccine (three-dose schedule, 3 different lots). To evaluate the long-term antibody persistence, volunteers will be bled at Years 11, 12, 13, 14 and 15 after the first vaccine dose of the primary vaccination course to determine their anti-HAV and anti-HBs antibody concentrations. No additional subjects will be recruited during the course of this long-term study. If a subject has become seronegative for anti-HAV antibodies or lost anti-HBs seroprotection concentrations at the long-term blood sampling time point (i.e. Years 11, 12, 13, 14 or 15), he/ she will be offered an additional vaccine dose.