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

To evaluate the long-term antibody persistence, volunteers will be bled at Years 6, 7, 8, 9 and 10 after the first vaccine dose of the primary vaccination course to determine their anti-HAV and anti-HBs antibody concentrations. 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 6, 7, 8, 9 or 10), he/ she will be offered an additional vaccine dose.