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.