The current extension study will assess the persistence of anti-HBs antibodies at Months 12, 24 and 36 after primary vaccination with Henogen's HBV vaccine or Fendrix™. This protocol posting deals with the objectives & outcome measures of the extension phase at Months 12, 24 and 36. The objectives & outcome measures of the primary phase are presented in a separate protocol posting (NCT00291941).

Subjects who received complete full vaccination with Henogen HBV adjuvanted vaccine or Fendrix™ will participate in this persistence study for three long-term time points (12, 24 and 36 months after the first dose of primary vaccination). Blood sampling will be done at each time point to measure immune persistence.

Inclusion Criteria:

• Written informed consent obtained from the subject/ from the parent/ guardian of the subject.
• Subjects who completed the full course of primary vaccination.

Exclusion Criteria:

• Immunosuppression caused by the administration of parenteral steroids or chemotherapy.
• Any confirmed or suspected human immunodeficiency virus (HIV) infection.