Inclusion Criteria:

• Toddler previously included in Study A3L10 who completed the three-dose primary series vaccination of either DTaP-IPV-HB-PRP~T or PENTAXIMÔ and ENGERIX B® at 2, 3 and 4 months of age.
• Toddler of 15 to 18 months of age (range: 456 to 578 days of age inclusive).
• Informed Consent Form signed by the parent(s) or other legal representative(s) and an institution official other than an Investigator.
• 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 second Visit.
• History of documented pertussis, tetanus, diphtheria, polio, Haemophilus influenzae type b or hepatitis B infection(s) (confirmed either clinically, serologically or microbiologically).
• Previous booster vaccination against pertussis, tetanus, diphtheria, polio or Haemophilus influenzae type b, and hepatitis B infection(s).
• Coagulopathy, thrombocytopenia or a bleeding disorder contraindicating intramuscular vaccination.
• Any vaccine-related SAE that occurred following the three-dose primary series administration of the investigational vaccine or of the reference vaccine in Study A3L10.
• 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.