The Aim of This Study is to Investigate the Persistence of Antibody Response in Adults up to 15 Years After One Booster Dose of GlaxoSmithKline (GSK) Biologicals' Encepur Adults Vaccine

Inclusion Criteria: Inclusion criteria for all subjects: * Subjects who, in the opinion of the investigator, can and will comply with the requirements of the protocol. * Written informed consent obtained from the subject prior to performance of any study specific procedure. * Subjects who have participated in study V48P7E2 (NCT01562444) and who received in the parent V48P7 study one of the following schedules: rapid, conventional, or accelerated conventional and a booster vaccination in study V48P7E1 (NCT00387634) or before study V48P7E1 (NCT00387634) (only rapid schedule). Additional inclusion criteria for subjects who will need a second booster dose: * Healthy subjects as established by medical history and clinical examination before entering into the study. * Female subjects of non-childbearing potential may be enrolled in the study. Non-childbearing potential is defined as pre-menarche, current bilateral tubal ligation or occlusion, hysterectomy, bilateral ovariectomy or post-menopause. * Female subjects of childbearing potential can receive the booster vaccine in the study, if the subject: has practiced adequate contraception for 30 days prior to vaccination, and has a negative pregnancy test on the day of vaccination, and has agreed to continue adequate contraception for 2 months after booster administration. Exclusion Criteria: Each subject must not be: * Unwilling or unable to give written informed consent to participate in the study. * Perceived to be unreliab…