Comparison of influenza vaccine regimens in pediatric patients:immunity and efficacy in 2014–15

Abstract

Abstract Currently, there are two types of influenza vaccines available to children and adolescents, Influenza Inactivated Vaccine (IIV) which is administered intramuscularly, and Live Attenuated Influenza Vaccine (LAIV) which is administered intranasally. The present study was designed to compare the efficacy of the two vaccines in pediatric patients in eliciting immune responses and protecting against infection in the 2014–15 influenza season. To conduct the study, patients ranging from ages 3 to 17 years were recruited for vaccination and evaluation. Patients were segregated by age (3 to 8 vs. 9 to17) and vaccine (IIV vs. LAIV). Peripheral blood samples were collected between the months of August and December, 2014 and processed for collection and storage of serum, plasma and peripheral blood mononuclear cells (PBMC). Each child who agreed to participate in the study was prescreened, consented and provided blood samples at three time points: D0 (blood drawn prior to vaccination), D7 and D21 following influenza vaccination. At the end of the vaccination season and once all enrolled patient samples had been collected, antibody responses were evaluated for reactivity to the vaccine strains as well as against additional circulating or heterogonous strains of influenza. Early in the 2014–15 season, it became apparent that the LAIV strain in the vaccine was not well matched to the circulating strain of influenza, resulting in less-than-effective immunity. Therefore, our analyses focused on IIV only. Our results showed that all participants in the study demonstrated higher titers and increased breadth of reactivity to diverse influenza strains when vaccinated with IIV, regardless of prior vaccination history.</jats:p