Long-term Persistence of Immunity Against Hepatitis B in 7-8 Years Old Children After Hepatitis B Vaccination.

Inclusion Criteria: * Subjects who the investigator believes that their parents/guardians can and will comply with the requirements of the protocol. * A male or female of 7 to 8 years of age (from and including the 7th birthday up to but excluding the 9th birthday) at the time of enrolment. * With documented evidence of previous vaccination with three consecutive doses of Engerix™-B in Germany * Written informed consent obtained from the parents or guardians of the subject at the time of enrolment. * Healthy subjects as established by medical history and clinical examination before entering into the study. Exclusion Criteria: * Concurrently participating in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product * Evidence of previous hepatitis B booster vaccination since administration of the third dose of Engerix™-B vaccine. * History of or intercurrent hepatitis B disease. * Hepatitis B vaccination at birth. * Planned administration/administration of a vaccine not foreseen by the study protocol during the period starting from 30 days before HBV vaccine challenge and ending 30 days after. * Administration of immunoglobulins and/or any blood products within the three months preceding HBV vaccine challenge or planned administration during the study period. * Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the HBV vaccine challenge. * Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination