<qa>  What vaccine will be administered at 2, 4 and 6 months of age?Participants in this Phase IIIb study will either receive GSK Biologicals combined diphtheria-tetanus-acellular pertussis-inactivated poliovirus DTPa-IPV vaccine or co-administration of GSK Biologicals combined diphtheria-tetanus-acellular pertussis DTPa vaccine and Sanofi-Pasteurs inactivated poliovirus vaccine. Vaccines for both groups will be administered at 2, 4 and 6 months of age. Two blood samples will be collected during the course of the study: prior to vaccination and one month after the third vaccine dose. 