Antibody Persistence in Healthy Children After Primary and Booster DTaP-IPV-Hep B-PRP-T Vaccine or Control Vaccine

All participants must have received the primary series of vaccinations and a booster vaccination in Study A3L15 (NCT 00362336).

Participants will receive no vaccination in this study but will undergo immunologic assessments at 3.5 and 4.5 years of age.

Inclusion criteria

• Aged 3 years and a half on the day of inclusion (42 months ± 60 days)
• Informed consent form signed by a parent or other legally acceptable representative and by an independent witness if the parent or other legal guardian is illiterate.
• Subject and parent/ legally acceptable representative able to attend the scheduled visits and to comply with all trial procedures.
• Receipt of primary vaccination with 3 doses of either DTaP-IPV-Hep B-PRP-T or CombAct-Hib™ + Oral poliovirus vaccine (OPV) + Engerix™ B and a booster dose of either DTaP-IPV-Hep B-PRP-T or CombAct-Hib™+ OPV.

Exclusion criteria

• Participation in another clinical trial investigating a vaccine, drug, medical device, or a medical procedure in the 4 weeks preceding the inclusion in the trial.
• Incomplete primary and booster immunization at trial A3L15.
• Previous confirmed clinical, serological, or microbiological diagnosis of diphtheria, tetanus, whooping cough, poliomyelitis, Haemophilus influenza b or hepatitis B after completion of A3L15 Study.
• Subjects known to have received diphtheria, tetanus, pertussis, Haemophilus influenza b and hepatitis B vaccination after completion of A3L15 Study.
• Any vaccination within 30 days preceding inclusion, except for measles or poliovirus (monovalent) containing vaccines and pandemic influenza vaccines including pandemic H1N1-2009 strain, which may be received at least two weeks before the subject's blood sample collection
• Blood or blood-derived products received at the latest 3 months before inclusion, receipts of immunosuppressant drugs within the previous 3 months.
• Known or suspected congenital or acquired immunodeficiency since completion of A3L15 Study.
• Serious chronic illness occurring after receipt of the primary and booster series (e.g. leukemia, lymphoma [Tor B cells], Crohn's disease).
• Known or suspected subject seroconversion for human immunodeficiency virus (HIV) or hepatitis C seropositivity since completion of A3L15 Study.
• Febrile (temperature ≥ 38.0°C) or acute, moderate or severe systemic illness on the day of inclusion.