The SCR was defined as the percentage of subjects with either a prevaccination HI titer <1:10 and a postvaccination HI titer ≥1:40 or a prevaccination HI titer ≥1:10 and a ≥4-fold increase in postvaccination HI titer. For assessment if SCR using HI assay, aTIV-1 and aTIV-2 vaccine groups were pooled for the analysis of A-H1N1 and A-H3N2 strains. For B-Victoria TIV=aTIV-1. For B-Yamagata TIV=aTIV-2.
The immunologic superiority in HI antibody responses for the alternate B strain (eg, the influenza B strain included in the aQIV but not in the aTIV formulation) were assessed for each aTIV separately, using the difference in SCR (aTIV-aQIV) at Day 22.