This is a study to assess the immunogenicity and safety of GlaxoSmithKline (GSK) Biologicals live attenuated measles-mumps-rubella-varicella vaccine given to healthy children in their second year of life.

Inclusion Criteria:

• A male or female subject between 11-13 months of age (i.e. from 11 month birthday until the day before the 14 month birthday) at the time of the first vaccination.

Exclusion Criteria:

• History of previous measles, mumps, rubella and/or varicella vaccination or disease, or known exposure to any of these diseases within 30 days prior to the start of the trial
• Planned administration of a vaccine not foreseen by the study protocol from 30 days prior to each vaccination until 42-56 days after each vaccination

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.