Immunogenicity Study of Antibody Persistence and Booster Effect of DTaP-HB-PRP~T Combined Vaccine or Tritanrix-HepB/Hib™

Inclusion Criteria: * Toddler aged 15 to 18 months of age on the day of inclusion (range: 456 days to 578 days of age inclusive) * Participated in the AL203 study and completed the three-dose primary series with either DTaP-HB-PRP\~T or Tritanrix-HepB/Hib™, and OPV, at 6, 10 and 14 weeks of age * Informed consent form signed by one parent or legal representative if appropriate (independent witness mandatory if parent is illiterate) * 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 trial vaccination * Planned participation in another clinical trial during the present trial period * Congenital or acquired immunodeficiency, immunosuppressive therapy such as long-term (for more than 2 weeks) systemic corticosteroid therapy within the preceding 3 months * Known 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 trial vaccination * Vaccination planned in the 4 weeks following the trial vaccination * Febrile (temperature ≥ 38.0°C) or acute illness on the day of inclusion * History of documented diphtheria, tetanus, pertussis, Haemophilus influenzae type b, hepatitis B or poliomyelitis infection(s) (confirmed either clinically, serologically, or microbiologically) * Vaccination with a vaccine containing diphtheria, tetanus, pertussis, Haemophilus influenzae type b, hepatitis B, or poliovirus 3 types antigen since the end of the primary series * Thrombocytopenia or a bleeding disorder contraindicating intramuscular (IM) vaccination * Serious adverse event related to any vaccination in the AL203 study.