- To describe the effect of a booster dose of DTaP-HB-PRP~T on immunogenicity at 12 to 18 months following a three-dose primary series vaccination of either DTaP-HB-PRP~T or Tritanrix HepB/Hib™ given at 6, 10 and 14 weeks of age, and one dose of Hep B vaccine given at birth.