Study of the DTaP-IPV-Hep B-PRP~T Combined Vaccine Following a Primary Series of DTacP IPV-HepB-PRP-T or Infanrix Hexa™

Inclusion Criteria: * Toddlers previously included in Study A3L11 (NCT00404651) who completed the three-dose primary series vaccination of either DTaP-IPV-HepB-PRP-T or Infanrix hexa™ at 2, 4 and 6 months of age * Toddlers of 15 to 18 months (456 to 578 days) of age, inclusive * Informed Consent Form signed by at least one parent or legal representative and two mandatory witnesses * Able to attend all scheduled visits and to comply with all trial procedures. Exclusion Criteria: * Participation in another clinical trial in the 4 weeks preceding the booster vaccination. * Planned participation in another clinical trial during the present trial period. * Congenital or acquired immunodeficiency, immunosuppressive therapy such as long-term systemic corticosteroid therapy. * Systemic hypersensitivity to any of the vaccine components or history of a life threatening reaction to a vaccine containing the same substances. * Chronic illness at a stage that could interfere with trial conduct or completion. * Blood or blood-derived products received in the last 3 months. * Any vaccination in the 4 weeks preceding the booster vaccination. * Any vaccination planned until the next visit. * History of documented pertussis, tetanus, diphtheria, polio, Haemophilus influenzae type b or hepatitis B (HB) infection(s) (confirmed either clinically, serologically or microbiologically). * Administration of a vaccine against pertussis, tetanus, diphtheria, polio, Hib, and/or hepatitis B infection(s) since the end of participation in Study A3L11. * Coagulopathy, thrombocytopenia or a bleeding disorder contraindicating intramuscular vaccination. * Known maternal history of human immunodeficiency virus (HIV), Hepatitis B surface antigen (HbsAg) or Hepatitis C seropositivity. * Subjects with any related serious adverse event that occurred following the three-dose primary series administration of the investigational vaccine or of the reference vaccine in Study A3L11. * History of seizures. * Febrile (temperature ≥38.0°C) or acute illness on the day of inclusion * Known contraindication to further vaccination with a pertussis vaccine, i.e.: Encephalopathy; Temperature \>40.0°C within 48 hours following a vaccine injection, not due to another identifiable cause during the primary series; Inconsolable crying that occurred for \>3 hours within 48 hours following vaccine injection during the primary series; Hypotonic hyporesponsive episode within 48 hours following vaccine injection during the primary series; Seizures with or without fever within 3 days following vaccine injection.