Evaluation of Antibody Persistence & Immune Memory in Subjects Vaccinated During Adolescence With Twinrix™

This study will evaluate the immune response against Hepatitis-A (HAV) and Hepatitis B surface (HBs) antigen in healthy subjects aged 12 to 15 years (at the time of primary vaccination), who received vaccination course with GSK Biologicals' Twinrix Adult and Twinrix Junior vaccine, approximately 10 years ago in the primary study. The subjects will be invited for blood sampling at 11, 12, 13, 14 and 15 years after primary vaccination to evaluate the persistence of immune response. For subjects detected with decreased immunity, the presence of immune memory against hepatitis A \& B antigens will be investigated by the administration of a challenge dose of the appropriate vaccine 6 to 12 months after the Year 15 follow-up time-point.

No new subjects will be recruited during this booster phase of the study.


Eligibility Criteria:
Inclusion Criteria:

* Subjects who the investigator believes that they can and will comply with the requirements of the protocol should be enrolled in the study.
* A male or female who received the complete primary vaccination course according to his/her group allocation in the primary study
* Written informed consent obtained from the subject.

All subjects must satisfy the following criteria at entry into the challenge dose phase:

* A male or female who received the complete primary vaccination course according to his/her group allocation in the primary study.
* Subjects who participated in the long-term follow-up phase of the primary study and for whom the antibody concentrations were below specified value for anti-HAV antibodies and/ or for anti-HBs antibodies at the last available follow-up time-points.
* Subjects who the investigator believes that they can and will comply with the requirements of the protocol should be enrolled in the study.
* Written informed consent obtained from the subject.
* Healthy subjects as established by medical history and clinical examination before entering into the challenge dose phase of this study.
* If the subject is female, she must be of non-childbearing potential, i.e. either surgically sterilized; or, if of childbearing potential, she must be abstinent or have used adequate contraceptive precautions for 30 days prior to vaccination, have a negative pregnancy test and must agree to continue such precautions for two months after the vaccination.

Exclusion Criteria:

The following criteria should be checked at each follow-up visit. If any apply at study entry, the subject must not be included at that long-term follow-up visit.

* Use of any investigational or non-registered product (drug or vaccine) since the last blood sampling visit.
* Administration of a hepatitis A, hepatitis B or hepatitis combination vaccine since the primary vaccination course of the primary study.
* History of hepatitis A or hepatitis B infection.
* Administration of hepatitis A or hepatitis B immunoglobulins and/or any blood products within 3 months prior to blood sampling.

The following criteria should be checked before the challenge dose phase. If any apply, the subject must not be included in the challenge dose phase:

* Use of any investigational or non-registered product (drug or vaccine) within 30 days before the administration of the challenge dose or planned use during the study period outside the context of the study.
* Administration of a hepatitis A, hepatitis B or hepatitis combination vaccine between the primary vaccination course of the primary study and the challenge dose visit.
* History of hepatitis A or hepatitis B infection.
* Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the challenge dose.
* Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination (no laboratory testing required).
* History of allergic disease or reactions likely to be exacerbated by any component of the vaccines.
* Acute disease at the time of.
* Administration of immunoglobulins and/or any blood products within the three months preceding the administration of the challenge dose or planned administration before the final blood sampling point (one month after the challenge dose).
* Pregnant or lactating female.