Trial to Assess Safety, Tolerability, and Immunogenicity of Influenza Virus Vaccine, Trivalent, Types A & B, Live Cold-Adapted (FluMist) and Measles, Mumps, Rubella, and Varicella Vaccines Administered Concurrently to Healthy Children

Inclusion Criteria: * 12 to 15 months of age (not reached their 16th month birthday); * In good health; * Parent/guardian available by telephone or for home visits; * Ability of the parent/guardian to understand and comply with the requirements of the protocol; * Signed informed consent by parent/guardian; and * Up to date with the primary series of recommended vaccines per standard clinic practice and local vaccine availability. Exclusion Criteria: * Previous known measles, mumps, rubella or varicella disease; * Previous vaccination against measles, mumps, rubella or varicella disease; * Hypersensitivity to egg or egg protein; * Signs or symptoms of any immunosuppressive or immune deficiency disease or ongoing immunosuppressive therapy; or an immunosuppressed individual living in the same household; * Acute febrile (\>100.0oF \[37.8°C\] oral) illness or clinically significant upper respiratory illness within the 72 hours prior to enrollment; * Use of aspirin (acetylsalicylic acid) or aspirin-containing products in the month prior to enrollment, or expected use of aspirin while enrolled in this study; * Administration of any intranasal medication within two weeks prior to enrollment or expected receipt during this study; * Administration of any live virus vaccine within one month prior to enrollment through 30 days after Visit 3; * Administration of any inactivated vaccine within two weeks prior to enrollment through 30 days after Visit 3; * Participation in another investigational trial within one month prior to enrollment or expected enrollment in another investigational trial during this study; * Receipt of any blood product within three months prior to vaccination or expected receipt within the study duration; and * Any condition which, in the opinion of the investigator, would interfere with the interpretation or evaluation of the vaccines. * History of two or more episodes of medically attended wheezing illness by parent/guardian report. * History of medically attended wheezing illness or bronchodilator medication use within four weeks of enrollment by parent/guardian report.