Immunogenicity & Safety Study of GSK Biologicals' 208136 Vaccine Formulated With New Measles and Rubella Working Seeds

This study is undertaken to generate clinical data on GSK Biologicals' combined measles-mumps-rubella-varicella vaccine manufactured with measles and rubella obtained from newly established working seed viruses which are one passage further than the current working seed viruses. The measles-mumps-rubella-varicella vaccine manufactured with the current working seed viruses will serve as comparator. A seed lot system is a system according to which successive batches of a vaccine are derived from the same master seed virus. For routine production, a working seed lot is prepared from the master seed virus.