A phase III, double-blind, randomized, multicenter primary vaccination study to bridge the DTPa-HBV-IPV vaccine manufactured according to the large scale manufacturing process with the DTPa-HBV-IPV vaccine manufactured by the small scale manufacturing process when administered intramuscularly to infants at 2, 4 and 6 months of age, co-administered with Merck's Hib conjugate vaccine (Liquid PedvaxHIB®) in a separate injection at 2 and 4 months of age