The present clinical study will assess the immunogenicity as the primary objective and the reactogenicity as the secondary objective of Aventis Pasteur's DTacP-IPV// PRP~T combined vaccine (Pentavac™ or Pentaxim™) as a three-dose primary vaccination at 6, 10 and 14 weeks of age followed by a booster dose during the second year of life.

Safety:

This study will describe the safety after each dose of the primary series of the study's combined vaccine (Pentaxim™).

Inclusion Criteria:

• Aged 42 to 56 days inclusive on the day of inclusion
• Born at full term pregnancy (> 37 weeks) with a birth weight ≥ 2.5 kg
• Informed consent form signed by the parent(s) or other legal representative
• 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 (first) trial vaccination
• Planned participation in another clinical trial during the present trial period
• Congenital or acquired immunodeficiency, immunosuppressive therapy such as long-term systemic corticosteroids therapy
• Systemic hypersensitivity to any of the vaccine components or history of a life-threatening reaction to the trial vaccine or 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 past.
• Any vaccination preceding the trial vaccination (except BCG and hepatitis B)
• History of diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B or Haemophilus influenza type b (confirmed either clinically, serologically or microbiologically).
• Previous vaccination against the diphtheria, tetanus, pertussis, poliomyelitis diseases or Haemophilus influenza type b infection with the trial vaccine or another vaccine.
• Thrombocytopenia or a bleeding disorder contraindicating intramuscular vaccination
• History of/current seizures
• Febrile illness (rectal temperature ≥ 38.0°C or axillary temperature ≥ 37.4°C) or acute illness on the day of inclusion.