Inactivated Influenza Vaccine in Infants 10-22 Weeks of Age

Influenza virus is an important global cause of morbidity and mortality. Influenza A or B viruses cause epidemics of disease almost every winter in the United States with an average of 36,000 deaths and 114,000 hospitalizations each year during 1990s (superscript 1). Children have the highest rates of infection while adults greater than 50 years of age have the highest mortality rates (superscript 2). Influenza, however, is associated with hospitalizations in young infants. In a survey of the Tennessee Medicaid database over many years, Neuzil et. al reported hospitalization rates in children less than 6 months of age that were much higher than in older children, and the rates approached those over 65 years of age (superscript 3). This is a prospective, phase l, open-label, self-contained, four visits over a period of 7 months, pilot study of 50 healthy infants, aged 10-22 weeks, with history of up-to-date routine immunizations, to assess safety and immunogenicity of administering 2 pediatric doses (with a minimum 4 weeks apart) of 0.25 ml of trivalent Influenza vaccine (Fluzone®). Each of the 50 infants will receive two 0.25mL doses of preservative free Fluzone®, given a minimum of 28 days apart but no more than 42 days apart. Preservative-free Fluzone® will not be administered at the same time as other routine vaccines. Approximately 2-3 mLs of venous blood will be obtained prior to the first vaccination, approximately 4 weeks after the second vaccination and 6 months after the second vaccination for the measurement of neutralization and HAI titers. Infants will be closely monitored during the influenza season for respiratory symptoms, fever, or other influenza-like illnesses. They will be seen during these episodes and nasal washes will be collected for a viral screen that will include culture for influenza virus, respiratory syncytial virus (RSV), adenovirus and parainfluenza virus and rapid test for influenza and RSV. Blood collected at the follow up visit, 6 months after the second dose of Fluzone®, will be used to measure post season antibody titers to strains of influenza A and B.