A Study to Assess Antibody Persistence, Boostability & Safety in Previously Primed Subjects.

Assess Immune Persistence & Memory by Giving Plain PRP,PSA & PSC (10 Mths Age), & Immunogenicity & Safety of a Tritanrix™-HBV/Hib-MenAC/ Tritanrix™-HBV/Hib2.5 Booster (15-18 Mths Age) in Previously Primed Subjects

The purpose of the study is as follows:

• To evaluate the persistence of antibodies and the presence of immune memory induced by a 3-dose primary vaccination with Tritanrix™-HepB/Hib-MenAC (three formulations) in the study DTPwHB/HibMenACTT001 (CPMS No. 759346/001) by giving unconjugated PRP, PSA and PSC at 10 months age to one subset of subjects.
• To evaluate the persistence of all antibodies pertaining to primary vaccination and the booster response to Tritanrix™-HepB/Hib2.5 vaccine or Tritanrix™-HepB/Hib-MenAC vaccine at 15-18 months age in the other subset of subjects.

This study will be conducted in two stages:

At 10 months age, half of the subjects will receive a dose of plain meningococcal AC and PRP polysaccharide (PS) vaccine at 10 months age.

At 15 to 18 months age (DTP booster phase), all subjects will receive a booster dose of Tritanrix™-HepB/Hib-MenAC or Tritanrix™-HepB/Hib2.5.

Inclusion criteria:

• Healthy child 10 months that participated in the study DTPwHB/HibMenACTT001 (CPMS No. 759346/001), written informed consent obtained from the parents.

Exclusion criteria:

• Planned administration/ administration of a vaccine not foreseen by the study protocol during the period starting from 30 days before and ending 30 days after administration of study vaccines with the exception of oral polio vaccine (OPV).
• Use of any investigational or non-registered product (drug or vaccine) other than the study vaccines within 30 days preceding the first dose of study vaccine, or planned use during study period.
• Chronic administration (> 14 days) of immunosuppressants or other immune-modifying drugs within 6 months prior to the first vaccine dose.
• Previous booster vaccination against diphtheria, tetanus, pertussis, hepatitis B, serogroups A or C meningococcal disease and/or Hib since the last visit of study 759346/001.
• History of/known exposure to diphtheria, tetanus, pertussis, hepatitis B, serogroups A or C meningococcal and/or Hib disease.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus (HIV) infection.