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Table 2 Hemagglutination-inhibition antibody responses after QIV in the per-protocol immunogenicity cohort

From: A historically-controlled Phase III study in adults to characterize the acceptability of a process change for manufacturing inactivated quadrivalent influenza vaccine

Strain Time point Seropositive GMT MGI
n (%; 95% CI) value (95% CI) value (95% CI)
18–60 years >60 years 18–60 years >60 years 18–60 years >60 years
N = 56 N = 56 N = 56 N = 56 N = 56 N = 56
A/H1N1 Day 0 49 40 82.0 25.0
(87.5; 75.9–94.8) (71.4; 57.8–82.7) (54.9–122.5) (17.3–36.0)
Day 21 56 55 392.5 223.5 4.8 8.9
(100; 93.6–100) (98.2; 90.4–100) (305.4–504.4) (157.0–318.1) (3.3–7.0) (5.8–13.7)
A/H3N2 Day 0 49 40 45.3 23.2
(87.5; 75.9–94.8) (71.4; 57.8–82.7) (31.3–65.4) (16.4–32.8)
Day 21 56 55 215.4 160.1 4.8 6.9
(100; 93.6–100) (98.2; 90.4–100) (166.3–278.9) (115.7–221.4) (3.5–6.6) (4.7–10.1)
B strain (Victoria) Day 0 54 52 92.8 38.5
(96.4; 87.7–99.6) (92.9; 82.7–98.0) (66.5–129.4) (28.3–52.4)
Day 21 56 56 318.0 237.8 3.4 6.2
(100; 93.6–100) (100; 93.6–100) (251.4–402.3) (179.7–314.9) (2.5–4.6) (4.3–8.8)
B strain (Yamagata) Day 0 56 54 130.4 57.3
(100; 93.6–100) (96.4; 87.7–99.6) (92.8–183.2) (44.3–74.0)
Day 21 56 56 404.8 355.5 3.1 6.2
(100; 93.6–100) (100; 93.6–100) (323.1–507.2) (263.5–479.5) (2.4–4.0) (4.6–8.4)
  1. QIV, inactivated quadrivalent influenza vaccine; Seropositive, titer ≥1:10; GMT, geometric mean titer; MGI, mean geometric increase defined as the geometric mean of the ratio between pre-vaccination and post-vaccination reciprocal titers.