Assessment of GSK Biologicals' Tdap Candidate Vaccine Administered as a Booster (6th Dose) in Terms of Immunogenicity and Safety to Children and Adolescents Previously Vaccinated With Five Doses of an Acellular Pertussis-containing Vaccine.

A Phase III, Double-blinded, Randomized, Multicenter, Clinical Study to Assess the Safety and Immunogenicity of GSK Biologicals' Tdap 0.3 mg Candidate Vaccine When Given as a Booster Dose to Healthy School Children and Adolescents (9-13 Years of Age), Previously Vaccinated With a 5th Consecutive Dose of Acellular Pertussis-containing Vaccine, in Studies APV-118 or APV-120

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