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. To demonstrate the potential of an MF59-adjuvanted inactivated trivalent seasonal influenza vaccine (aIIV3; Fluad™) to improve the immune response in young children, we review the immunogenicity, efficacy, and safety/tolerability of aIIV3 from a comprehensive clinical development program in a pediatric population with a specific need for improved influenza vaccines. Data were analyzed from a series of 1 phase Ib, 3 phase II, and 2 phase III studies involving 11,942 children aged 6 months through 5years. The clinical data showed that aIIV3 had statistically significantly greater immunogenicity and efficacy in the prevention of influenza compared to conventional inactivated trivalent seasonal influenza vaccines (IIV3s). The safety profile of aIIV3 was generally similar to that of nonadjuvanted IIV3, apart from an increased frequency of solicited adverse events (AEs) following vaccination. The majority of solicited AEs were mild or moderate in severity and resolved within 1 to 3 days. aIIV3 was well tolerated, with immunogenicity and efficacy exceeding that of conventional IIV3 in children 6 months through 5years of age. The MF59-adjuvanted vaccine has the potential to fulfill an unmet clinical need in the prevention of seasonal influenza in this age group.