Influenza Vaccine Dose-Response in Infants and Toddlers: Immunogenicity and Reactogenicity

Inclusion Criteria: * Child healthy (stable chronic conditions acceptable) as established by health assessment interview and verbal history-directed health examination * Child between and including 6 months of age and 23 months of age (up to and including the day before 24 months of age) * Child is available and can complete all relevant procedures during the entire study period * Parent or legal guardian is available and can be reached by phone during the entire study period * Parent/guardian provides written informed consent * Parent/guardian is fluent in English Exclusion Criteria: * Child has history of laboratory-confirmed influenza * Child has history of any prior influenza immunization * Child has history of anaphylactic reaction to any component of the vaccine (i.e. egg) * Child has received immune globulin or other blood products within the prior six weeks * Child has received injected or oral steroids within the prior six weeks (inhaled or topical steroids allowed) * Child has a bleeding diathesis or condition associated with prolonged bleeding time that would contraindicate intramuscular injection (thrombocytopenia, coagulation disorder, anti-coagulant therapy) * Child is or will be enrolled in any other clinical trial of a drug, vaccine or medical device during the study period * Child is scheduled to receive a live vaccine (notably measles, mumps, rubella or varicella vaccines) during the study period * Child has a health condition which, in the opinion of the investigator, would interfere with the evaluation or pose a health risk to the child