Study to Show That the Combined Hepatitis A and B Vaccine is Non-inferior to Monovalent Vaccines in Adults

Inclusion Criteria: * Subjects who the investigator believes that they can and will comply with the requirements of the protocol. * A male or female who completed the primary vaccination phase of the study. * Written informed consent obtained from the subject. * If the subject is female, she must be of non-childbearing potential, or, if of childbearing potential, she must be abstinent or have used adequate contraceptive precautions for 30 days prior to vaccination, have a negative pregnancy test and must agree to continue such precautions for two months after completion of the vaccination series. Exclusion Criteria: * Use of any investigational or non-registered product other than the study vaccines within 30 days preceding the first dose of study vaccine, or planned use during the study period. * History of any hepatitis A or hepatitis B vaccination or infection, since the primary vaccination study. * History of allergic disease or reactions likely to be exacerbated by any component of the vaccine. * Acute disease at the time of enrolment. * Pregnant or lactating female.