Influenza Vaccine in Premature Infants

Background. Influenza is increasingly recognized as causing severe respiratory illness in children. High-risk infants, like former premature infants, and particularly those with lung disease, have influenza hospitalization rates about five times higher than healthy children. Influenza vaccine does not protect young children against influenza as well as it does healthy adults. A small study that measured antibodies (proteins that protect against infection) to influenza suggested that premature infants get even less protection from influenza vaccine than full-term infants. More information about influenza vaccine in premature infants is needed. The overall goals of this project are to collect information about the how well the influenza vaccine induces antibody production, and to develop the collaborative network of centers necessary for a larger trial of influenza vaccine in premature infants. Objective and Hypotheses. The objective of this study is to measure the amount of protective antibody produced by influenza vaccine in premature (less than 30 weeks' \[about 7 months\] gestation at birth), extremely-low-birth-weight (1000 grams \[2¼ pounds\] or less at birth) infants. Influenza vaccine needs to be given yearly. We will assess premature infants during their first series of influenza vaccines. We hypothesize that the levels of antibody will be lower in premature infants receiving their first series of influenza vaccine than in full-term infants. Design. We will measure the immune response in premature and full term infants. During the 2007-2008 influenza season, a total of 92 subjects, divided among 2 groups (premature infants 6-17 months old receiving their first influenza vaccine series and full-term infants 6-17 months old receiving their first influenza vaccine series) will be recruited at a consortium of five centers (the University of Rochester, the University of Texas Southwestern Medical Center, Wake Forest University, the University of Miami and the State University of New York at Buffalo), receive 2 doses of influenza vaccine, and have antibody and immune cell responses to each vaccine component measured 4-6 weeks after the second dose of vaccine. Potential Impact. If this study and future investigations suggested ways to improve premature infants influenza vaccine responses, they could lead to changes in recommendations for the number or timing of vaccine doses or of the type of vaccine used in this high-risk group.