Trial to Determine the Safety and Efficacy of Influenza Virus Vaccine, Trivalent, Types A & B, Live, Cold-Adapted (CAIV-T) in Healthy Children

Inclusion Criteria: * who are greater than or equal to 6 months and less than 36 months of age at the time of enrollment, and in good health as determined by medical history, physical examination, and clinical judgment; * whose parent or legal guardian has provided written informed consent after the nature of the study has been explained; * who, along with their parent or legal guardian, will be available for the duration of the study (24 months); * whose parent/legal guardian can be reached by study staff for the post-immunization contacts \[via telephone, clinic or home visits\]. Exclusion Criteria: * whose parents or caregiver are perceived to be unreliable or difficult to contact for evaluation or study visits during the study period; * with any serious chronic disease (e.g., with signs of cardiac or renal failure or severe malnutrition), including progressive neurological disease; * with Down's syndrome or other known cytogenetic disorders; * with a known or suspected disease of the immune system or those receiving immunosuppressive therapy, including systemic corticosteroids; * who received any blood products, including immunoglobulin, in the period from six months prior to vaccination through to the conclusion of the study; * for whom there is intent to administer any other investigational vaccine or agent from one month prior to enrollment through to the conclusion of the study; * with an immunosuppressed or compromised individual living in the same household; * who, at any time prior to entry into this study, received a dose of any influenza vaccine (commercial or investigational); * who were administered any live virus vaccine within one month prior to study vaccination or expected receipt of another live virus within one month of vaccination in this study; * with a documented history of hypersensitivity to egg or egg protein, or any other component of the study vaccines or placebo; * with a respiratory illness with wheezing within two weeks prior to enrollment; * who received aspirin (acetylsalicylic acid) or aspirin-containing products in the two weeks prior to enrollment or for which use is anticipated during the study; * with any medical conditions that in the opinion of the Investigator might interfere with interpretation of the study results; Note: A pregnant household member or day care provider is not considered a contraindication to enrollment.