The Effect of Prophylactic Antipyretics on Immune Responses and Fever After 2014-2015 and 2015-2016 Inactivated Influenza Vaccine

This study aims to conduct a double-blind, placebo-controlled study to assess the effect of prophylactic antipyretics on the immune responses and rates of fever after inactivated influenza vaccine (IIV) in children 6 through 47 months of age. In this study, 160 healthy children, 6 through 47 months of age, including some children at risk of febrile seizure, will be randomized to one of three different treatment arms. Children will receive either blinded therapy with prophylactic acetaminophen or placebo immediately following and every 4 to 6 hours in the 24 hours after receipt of a dose of IIV or open-label ibuprofen every 6 to 8 hours in the 24 hours after receipt of a dose of IIV. Children will be followed for the occurrence of fever, fussiness, changes in appetite and sleep patterns, and use of medical services on the day of and for two days following vaccination. Antibody to influenza antigens contained in the respective 2014-2015 and 2015-2016 vaccines as measured by hemagglutination inhibition (HAI) antibody will be assessed at baseline and four weeks following vaccination. The proportions of children experiencing fever, having solicited side effects, using medical services, demonstrating a serologic response corresponding to seroprotection and seroconversion to each of the IIV antigens will be determined for groups of children in each of the three treatment arms. Likewise geometric mean HAI titers (GMTs) and corresponding 95% confidence intervals for each IIV antigen will be calculated for the three treatment arms. The investigators hope to learn whether or not prophylactic antipyretics affect the immune response and fever rates following IIV.