Trial to Investigate Immune Responses Elicited by a Liquid Formulation of Influenza Virus Vaccine,(CAIV-T)

Inclusion Criteria: * Healthy adults aged 18 to 59 years or \> 60 years. * Female subjects of childbearing potential who had a negative urine pregnancy test result prior to study vaccination. Females who were surgically sterilized or post-menopausal did not require pregnancy testing. * Adults who were determined by medical history, physical examination and clinical judgment eligible for this study. Subjects with stable pre-existing disease, defined as disease not requiring change in therapy or hospitalization within 12 weeks before receipt of study vaccination, were eligible. * Subjects who provided written informed consent after the nature of the study was explained. * Subjects who were available for the duration of the study (from enrollment to study completion). * Subjects who could be reached by study staff for the post-vaccination contact \[via telephone, clinic or home visit\]. Exclusion Criteria: * Subjects who resided in a nursing home or long-term care facility or other institution receiving skilled or semi-skilled nursing care. An ambulatory subject who resided in a retirement home or village was eligible for participation. * Subjects with evidence of dementia or other severe cognitive impairment based on Mini Mental State Examination (MMSE) score of 22 or greater. Note: Administration of MMSE was performed only if clinically indicated. For all study subjects: * Subjects who were perceived to be unavailable or difficult to contact for evaluation of study visits during the study period. * Subjects with a known or suspected disease of the immune system or those receiving immunosuppressive therapy, including systemic corticosteroids; or cytotoxic agents. * Subjects who received any blood products, including immunoglobulin, in the period from six months prior to vaccination through to the conclusion of the study. * Subjects who resided in the same household as an immunosuppressed or immunocompromised individual. * Subjects with a documented history of hypersensitivity to egg or egg protein or any other component of the study vaccine or placebo. * Subjects who were administered any live virus vaccine within one month prior to enrollment. * Subjects for whom there was intent to administer any other investigational vaccine or agent from one month prior to enrollment through the conclusion of the study. * Subjects who received a dose of influenza treatment (commercial or investigational) one month prior to enrollment. Prophylactic use of influenza antivirals was not permitted. * Subjects who received any influenza vaccine in the six months prior to enrollment, or nonstudy influenza vaccine since enrollment. * Subjects with any medical conditions that in the opinion of the investigator might interfere with the interpretation of the study results.