Long-term Study of Immune Response Persistence of GSK Biologicals' 2-dose Thiomersal-free Engerix™-B and 3-dose Preservative-free Engerix™-B Vaccines in Subjects Aged 11-15 Yrs

To evaluate the persistence of antibodies against hepatitis B at 30, 42, 54 and 66 months after the first dose of the hepatitis B primary vaccination course. Subjects were aged 11 to 15 years at the time of the primary vaccination course. At the time of enrollment in the present long-term follow-up study subjects were aged 13 to 18 years. The Protocol Posting has been updated in order to comply with the FDA Amendment Act, Sep 2007.