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

The purpose of this study is to compare the antibody response and reaction rates in children age 6-23 months when they are given either the currently recommended schedule of two 0.25ml doses of influenza vaccine one month apart or two 0.5ml doses of influenza vaccine, one month apart.

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