Adjusted GMT ratios on Day 21 (ATP cohort for immunogenicity). Adjusted GMT ratios for A/Solomon Islands, A/Wisconsin, B/Malaysia and B/Jiangsu (only included in QIV formulations) on Day 21 for all treatment groups in the per-protocol cohort for immunogenicity. The margin for superiority of response was if the 95% CI lower limit was ≥1 and the margin for non-inferiority of response was if the 95% CI lower limit was ≥0.67. The data points represent the adjusted GMT ratio for QIV group over the TIV group (QIV/TIV; diamond) or the LD QIV-AS group over the LD TIV-AS group (LD QIV-AS/LD TIV-AS; square) with their associated 95% confidence intervals (CIs). Abbreviations: LD QIV-AS: low-dose adjuvanted quadrivalent influenza vaccine; LD TIV-AS: low-dose adjuvanted trivalent influenza vaccine; QIV: quadrivalent influenza vaccine; TIV: trivalent influenza vaccine.