Immunogenicity and Safety of GlaxoSmithKline Biologicals' MMRV Vaccine vs. ProQuad® in Children 12-14 Months of Age

Inclusion Criteria: * Subjects for whom the investigator believes their parents/guardians can and will comply with the requirements of the protocol. * Male or female between 12 and 14 months of age at the time of first vaccination. * Written informed consent obtained from the parent/guardian of the subject. * Healthy subjects as established by medical history and clinical examination before entering into the study. * Have previously received 3 doses of 7-valent pneumococcal conjugate vaccine within the first year of life. Exclusion Criteria: * Use of any investigational or non-registered product other than the study vaccine(s) within 30 days preceding the first dose of study vaccine, or planned use during the study period. * Concurrently participating in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product. * Chronic administration of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose. * Planned administration/ administration of a vaccine not foreseen by the study protocol from 30 days prior to vaccination until 42 days after vaccination, except for influenza vaccine. * Previous vaccination against measles, mumps, rubella and/or varicella. * Previous vaccination against hepatitis A or receipt of a fourth dose of pneumococcal conjugate vaccine. * History of measles, mumps, rubella and/or varicella/zoster diseases. …