Persistence of anti-HBs antibodies at Month 24, 30 and 36 in subjects who had completed primary vaccination was evaluated. The anamnestic response to a booster dose was evaluated in subjects with anti-HBs antibody titres < 10 mIU/ml at previous timepoint. The study also evaluated the effect of a booster dose of the vaccine (Month 42) after primary vaccination.

Inclusion Criteria:

• Subjects were to have completed primary vaccination course. A male or female > = 15 years of age at the time of the first vaccination.
• Written informed consent obtained from the subject/ from the parents or guardians of the subject.
• If the subject was a female, she was of non-childbearing potential or, if of childbearing potential, she was to be abstinent or use adequate contraceptive precautions for one month prior to enrollment and up to two months after the last vaccination.

Exclusion Criteria:

• Use of any investigational or non-registered drug or vaccine other than the study vaccine within 30 days preceding the booster dose of study vaccine, or planned use during the study period.
• Pregnant or lactating female.