Immunogenicity & Safety Study of GSK Biologicals' Combined Measles-mumps-rubella-varicella Vaccine 208136

Inclusion Criteria: * Subjects who the investigator believes that their parents/guardians can and will comply with the requirements of the protocol should be enrolled in the study. * A male or female between, and including 11 and 24 months of age, at the time of the vaccination. * Written informed consent obtained from the parent or guardian of the subject. * Healthy subjects as established by medical history and clinical examination before entering into the study. Exclusion Criteria: * Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine(s) within 30 days preceding the dose of study vaccine, or planned use during the study period. * Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the vaccine dose. * Administration of immunoglobulins and/or any blood products during the six months before entering the study or planned administration during the study period. * Planned administration/ administration of a vaccine not foreseen by the study protocol within 30 days prior to until 42 days after the study vaccine dose with the exception of inactivated vaccines such as pneumococcal, Haemophilus influenzae type b conjugate vaccines, inactivated influenza, hepatitis A or B vaccine or diphtheria/tetanus-containing vaccines which can be administered up to eight days before the study vaccine dose. * Previous vaccination against measles, mumps, rubella and/or varicella. * History of measles, mumps, rubella and/or varicella/zoster diseases. * Known exposure to measles, mumps, rubella and/or varicella within 30 days prior to study start. * Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus (HIV) infection. * A family history of congenital or hereditary immunodeficiency. * History of allergic disease or reactions likely to be exacerbated by any component of the vaccine(s), including systemic hypersensitivity to neomycin. * Major congenital defects or serious chronic illness. * Acute disease at the time of enrolment. * Rectal temperature ≥ 38°C or axillary temperature ≥ 37.5°C at the time of vaccination. * Residence in the same household as a high risk person e.g.: * New-born infants (0-4 weeks of age) * Pregnant women who have a negative history of chickenpox * Persons with known immunodeficiency