Long-term Follow-up on Immunogenicity & Safety of Measles-Mumps-Rubella-Varicella (MMRV) Combined Vaccine

Inclusion Criteria: * Written informed consent from the parents/guardians of the child before participating in the long-term follow-up. * Subjects must have received their complete vaccination course according to the group allocation (i.e. subjects must have received either two doses of MMRV combined vaccine, or two doses of Priorix vaccine and one dose of Varilrix vaccine as separate injections in the primary vaccination study. * Subjects were aged between 12 to 18 months of age at the time of the first vaccination in the primary study. Exclusion Criteria: * Subjects must not have received an additional dose of measles, mumps, rubella or varicella containing vaccines.