The primary objective of this study is to estimate the relative efficacy and assess the safety of CAIV-T compared to TIV.

Inclusion Criteria:

• Age 6-59 months of age (not yet reached their 5th birthday)
• Parent or guardian available by telephone
• Available for illness visits at clinic or at home during the influenza surveillance period
• Written informed consent (and Health Insurance Portability and Accountability Act [HIPAA] authorization for U.S. Participants) obtained from the participant's parent or legal guardian and
• Ability of the parent/guardian to understand and comply with the requirements of the protocol

Exclusion Criteria:

• History of hypersensitivity to any component of CAIV-T or inactivated influenza vaccine, including egg or egg protein
• History of hypersensitivity to gentamicin
• Any known immunosuppressive condition or immune deficiency disease (including HIV infection), or ongoing receipt of any immunosuppressive therapy
• History of Guillain-Barre syndrome
• Medically-diagnosed wheezing, bronchodilator use, or steroid use (systemic or inhaled) within the previous 42 days by parent report or chart review (e.g., children with recent persistent asthma are excluded), or history of severe asthma
• Acute febrile (>100.0 degrees F or >37.8 degrees C oral or equivalent) illness or acute respiratory illness, including sore throat, within three days prior to enrollment
• Receipt of an investigational product within 30 days prior to enrollment or expected receipt during this study
• Use of aspirin or salicylate-containing products 30 days prior to enrollment or expected receipt during this study
• Use of anti-influenza medications (including amantadine, rimantadine, oseltamivir, and zanamivir) within 14 days prior to enrollment or expected receipt during this study
• Receipt of any blood product within 90 days prior to vaccination or expected receipt during this study
• Administration of any live virus vaccine within 30 days prior to enrollment, or if receipt of another live virus vaccine is expected within 30 days of any study vaccination
• Administration of any inactivated vaccine within 14 days prior to enrollment or if receipt of another inactivated vaccine is expected within 14 days prior to enrollment or if receipt of another inactivated vaccine is expected within 14 days of any study vaccination
• Close contact who is severely immunocompromised (e.g., transplant recipient)
• Family member or household contact who is an employee of the research center or otherwise involved with the conduct of the study and
• Any condition that, in the opinion of the investigator, might interfere with the interpretation or evaluation of the vaccines.