The purpose of this study is to assess the immunogenicity, safety and reactogenicity of the booster vaccine dose of 2 new formulations of DTPa-HBV-IPV/Hib administered between 12 and 15 months of age, and the immune persistence following the primary series. All children in this booster study received a primary vaccination at 2, 3 and 4 months of age in study 113948 (NCT01248884). No new subjects will be enrolled in this booster study.