The aims of this study are to evaluate the safety and immunogenicity of a booster dose of GSK Biological's candidate Tdap vaccine containing 0.3 mg Al when administered to healthy school children and adolescents (9-13 years of age) previously vaccinated with five consecutive doses of Pa-containing vaccine. The inclusion of hepatitis A vaccine (Havrix®) as a control vaccine enables this study to be conducted in a double-blinded in terms of immunogenicity and safety assessments.

Inclusion Criteria:

- Subjects previously enrolled and vaccinated in GSK Biologicals' studies APV-118 and APV-120 and who were 9 through 13 years of age

Exclusion Criteria:

• Use of any investigational or non-registered drug or vaccine other than the study vaccines within 30 days preceding the administration of study vaccines, or planned use during the study period.
• Chronic administration or planned administration of immunosuppressants or other immune modifying drugs within six months prior to study vaccination or planned administration during the study period
• Administration of immunoglobulins and/or blood products within 3 months prior to vaccination

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.