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

Inclusion Criteria: * who are aged at least 6 months and less than 36 months of age at the time of enrollment, attending day care for at least three days a week, four hours a day; * who are in good health as determined by medical history, physical examination and clinical judgement; * whose parent(s)/legal guardian(s) have provided written informed consent after the nature of the study has been explained; * who, along with their parent(s)/legal guardian(s), will be available for duration of the trial (8 months ± 1 month); * whose parent(s)/legal guardian(s), can be reached by study staff for the post-vaccination contacts \[telephone, clinic or home visit\]. Exclusion Criteria: * whose parent(s)/legal guardian(s) are perceived to be unavailable 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; * have an immunosuppressed or an immunocompromised 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, in the two weeks prior to entry into this study, received a dose of any influenza treatment (commercial or investigational); * with a documented history of hypersensitivity to egg or egg protein or any other component of the study vaccine or placebo; * with a clinically confirmed 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; * who were administered any live virus vaccine within one month prior to enrollment or expected to receive another live virus vaccine within one month of vaccination in this study; * with any medical conditions that in the opinion of the investigator might interfere with interpretation of the study results; If any of these criteria are met following enrolment, the subject will be excluded from subsequent vaccine dosing. Note: A pregnant household member is not considered a contraindication to enrollment.