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Table 4 Hemagglutination-inhibition antibody response at 21 days following vaccination (ATP cohort subset for immunogenicity)

From: Challenge of conducting a placebo-controlled randomized efficacy study for influenza vaccine in a season with low attack rate and a mismatched vaccine B strain: a concrete example

    Influenza A (H1N1)
A/New Caledonia/20/99 (H1N1) IVR-116
Influenza A (H3N2)
A/New York/55/2004 (H3N2) X-157
Influenza B
B/Jiangsu/10/2003 virus
  CHMP
acceptance
criteria**
CBER
acceptance criteria***
TIV
N = 632
Placebo
N = 315
TIV
N = 632
Placebo
N = 315
TIV
N = 632
Placebo
N = 315
Geometric Mean Titer (GMT) No Standard No Standard 730.5
[648.1–823.3]
11.6
[10.2–13.3]
131.7
[119.9–144.6]
13.5
[11.9–15.3]
191.1
[175.7–207.9]
17.9
[15.7–20.3]
% Sero-conversion rate * % > 40% LL of 95% CI > 40% 89.2
[86.6–91.5]
0.0
[0.0–1.2]
77.2
[73.7–80.4]
0.3
[0.0–1.8]
82.9
[79.7–85.8]
0.0
[0.0–1.2]
% Sero-protection
(titer ≥ 40)
% > 70% LL of 95% CI > 70% 97.8
[96.31–98.78]
21.9
[17.46–26.88]
88.1
[85.35–90.55]
22.5
[18.04–27.56]
95.9
[94.03–97.30]
30.2
[25.14–35.56]
  1. * Seroconversion rate for Hemagglutination-inhibition antibody response is defined as the percentage of vaccinees who have a prevaccination titer < 1:10 and a post-vaccination titer ≥ 1:40, or who have a prevaccination titer ≥ 1:10 and at least a fourfold increase in post-vaccination titer