Background: Children are at high risk of acquiring and transmitting influenza infection and are a high priority group for influenza vaccination.
Methods: This was a randomized, observer-blind, multicenter study (NCT00980005) based in the United States. Children were randomized (1:1) to receive either the study vaccine, a thimerosal-free trivalent inactivated influenza vaccine or an active comparator (control vaccine) and were allotted to 1 of 3 age categories: 3-4, 5-8 and 9-17 years. The primary objective was to show noninferiority of the study vaccine versus a US- licensed control influenza vaccine.
Results: A total of 2116 children were vaccinated (study vaccine N = 1055, control vaccine N = 1061). The predefined noninferiority criteria and the Center for Biologics Evaluation and Research criteria for clinical benefit were met for all 3 seasonal virus strains in all children and each age strata. The ratios of the adjusted geometric mean titers (control vaccine over study vaccine) ranged from 0.93 to 1.03 for the 3 virus strains whereas the differences in seroconversion rate (control vaccine minus study vaccine) were between -2.42% and -1.60%. Postvaccination geometric mean titers (range: 213.7-414.7 versus 200.2-451.9) and seroconversion rates (range: 59.8-81.1% versus 58.2-78.6%) were comparable for the 2 vaccines. The safety and reactogenicity profiles were similar for both treatment groups in all age strata.
Conclusions: Immunologic noninferiority of the study vaccine was demonstrated compared with the control vaccine. Furthermore, the study vaccine had a similar safety profile as the control vaccine in children.