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Table 3 Hemagglutination-inhibition antibody responses after QIV according to previous seasonal influenza vaccination history 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 Previous vaccination† Timepoint SPR SCR MGI
n/N (%; 95% CI) n/N (%; 95% CI) N; value (95% CI)
18–60 years >60 years 18–60 years >60 years 18–60 years >60 years
N = 28 N = 28 N = 28 N = 28 N = 28 N = 28
A/H1N1 Yes Day 0 25/28 16/28
(89.3; 71.8–97.7) (57.1; 37.2–75.5)
   Day 21 28/28 25/28 10/28 9/28 28; 3.1 28; 3.5
(100; 87.7–100) (89.3; 71.8–97.7) (35.7; 18.6–55.9) (32.1; 15.9–52.4) (2.0–4.9) (2.3–5.2)
  No Day 0 19/28 10/28
(67.9; 47.6–84.1) (35.7; 18.6–55.9)
   Day 21 27/28 27/28 18/28 25/28 28; 7.4 28; 22.9
(96.4; 81.7–99.9) (96.4; 81.7–99.9) (64.3; 44.1–81.4) (89.3; 71.8–97.7) (4.1–13.3) (12.7–41.2)
A/H3N2 Yes Day 0 21/28 19/28
(75.0; 55.1–89.3) (67.9; 47.6–84.1)
   Day 21 27/28 26/28 9/28 13/28 28; 2.7 28; 3.4
(96.4; 81.7–99.9) (92.9; 76.5–99.1) (32.1; 15.9–52.4) (46.4; 27.5–66.1) (2.0–3.6) (2.5–4.7)
  No Day 0 13/28 9/28
(46.4; 27.5–66.1) (32.1; 15.9–52.4)
   Day 21 27/28 27/28 18/28 22/28 28; 8.5 28; 13.8
(96.4; 81.7–99.9) (96.4; 81.7–99.9) (64.3; 44.1–81.4) (78.6; 59.0–91.7 (5.2–13.9) (7.4–25.6)
B strain (Victoria) Yes Day 0 26/28 17/28
(92.9; 76.5–99.1) (60.7; 40.6–78.5)
   Day 21 28/28 27/28 4/28 12/28 28; 2.4 28; 3.3
(100; 87.7–100) (96.4; 81.7–99.9) (14.3; 4.0–32.7) (42.9; 24.5–62.8) (1.7–3.3) (2.3–4.9)
  No Day 0 21/28 14/28
(75.0; 55.1–89.3) (50.0; 30.6–69.4)
   Day 21 28/28 28/28 15/28 21/28 28; 4.9 28; 11.5
(100; 87.7–100) (100; 87.7–100) (53.6; 33.9–72.5) (75.0; 55.1–89.3) (3.0–7.9) (6.8–19.2)
B strain (Yamagata) Yes Day 0 27/28 24/28
(96.4; 81.7–99.9) (85.7; 67.3–96.0)
   Day 21 28/28 28/28 6/28 12/28 28; 2.1 28; 4.1
(100; 87.7–100) (100; 87.7–100) (21.4; 8.3–41.0) (42.9; 24.5–62.8) (1.6–2.7) (2.6–6.5)
  No Day 0 21/28 21/28
(75.0; 55.1–89.3) (75.0; 55.1–89.3)
   Day 21 28/28 28/28 14/28 23/28 28; 4.6 28; 9.4
(100; 87.7–100) (100; 87.7–100) (50.0; 30.6–69.4) (82.1; 63.1–93.9) (3.1–6.9) (6.4–13.8)
  1. †Received (yes) or did not receive (no) seasonal influenza vaccine during the preceding season (2010–2011); QIV, inactivated quadrivalent influenza vaccine; n/N, number fulfilling definition of response/total number in group; SCR, seroconversion rate defined as the proportion with antibody titer <1:10 at baseline and with post-vaccination titer of ≥1:40, or pre-vaccination titer of ≥1:10 and a ≥4-fold post-vaccination increase in titer; SPR, seroprotection rate defined as proportion with post-vaccination titer ≥1:40; MGI, mean geometric increase defined as the geometric mean of the ratio between pre-vaccination and post-vaccination reciprocal titers; Immune responses were assessed according to the to the European Union Committee for Medicinal Products for Human Use (CHMP) licensure criteria: to fulfil the criteria the point estimates for SCR needed to be >40%, for SPR >70%, and MGI >2.5 in the 18–60 years group, and SCR >30%, for SPR >60%, and MGI >2.0 in the >60 years group [21].