Safety Study of Measles-Mumps-Rubella-Varicella (MMRV) Vaccine, Priorix-Tetra™ in Children Living in the Philippines

Inclusion Criteria: * Subjects who the investigator believes that parent(s)/Legally Acceptable Representative(s) \[LAR(s)\] can and will comply with the requirements of the protocol. * Written informed consent obtained from the parent(s)/LAR(s) of the subject. * Male or female subjects living in the Philippines between, and including, the ages of 12 months and 12 years at the time of the vaccination. * Female subjects of child bearing potential may be enrolled in the study, if the subject: * has agreed to be abstinent or practiced adequate contraception for 30 days prior to vaccination, and * has a negative pregnancy test on the day of vaccination, and * has agreed to continue adequate contraception during the entire treatment period and for 3 months after completion of the vaccination. Exclusion Criteria: * Child in care. * Any contraindications to vaccination as stated in the Prescribing Information. * Acute, severe febrile illness at the time of enrollment. The presence of a minor infection, such as a cold, will not exclude the subject from the study. * Previous receipt of a measles, mumps, rubella and/or varicella-virus containing vaccine less than 3 months prior to study entry. * Previous enrolment in this trial. * Subjects with impaired immune function, including primary or secondary immunodeficiencies based on medical history. * History of hypersensitivity to any component of the vaccine. * History of hypersensitivity following previous administration of measles, mumps, rubella and/or varicella-virus containing vaccines. * Receipt of human gamma globulins or a blood transfusion within 3 months prior to study entry. * Hypersensitivity to latex. * Pregnant or lactating female.