Cumulative Clinical Experience with MF59-Adjuvanted Trivalent Seasonal Influenza Vaccine in Young Children.

•The immune response to aIIV3 is superior to IIV3 in pediatric subjects (N=11,942).•More children achieve protective HI antibody responses with aIIV3 than with IIV3.•aIIV3 has higher immune responses than IIV3 to homologous and heterologous strains.•Absolute and relative efficacy against influenza were higher with aIIV3 than IIV3.•Solicited AEs, mostly mild to moderate in severity, were more frequent with aIIV3.