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.

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.