The present clinical study will assess the immunogenicity and reactogenicity of Sanofi Pasteur's DTacP-IPV// PRP~T combined vaccine (Pentavac™ or Pentaxim™) as a three-dose primary vaccination at 2, 4, and 6 months of age followed by a booster dose during the second year of life and concomitant hepatitis B vaccine at 2 and 6 months of age in infants in Thailand.

Inclusion Criteria:

• Aged 53 to 70 days inclusive on the day of inclusion

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 corticosteroid 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.
• Mother known as seropositive to HIV or hepatitis B
• Any vaccination in the 5 weeks preceding the first trial vaccination (except Bacille Calmette-Guerin [BCG])
• History of diphtheria, tetanus, pertussis, poliomyelitis, Haemophilus influenzae type b infection or hepatitis B (confirmed either clinically, serologically or microbiologically).
• Previous vaccination against the diphtheria, tetanus, pertussis, poliomyelitis diseases or Haemophilus influenzae 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.