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Table 5 Hemagglutination-inhibition antibody responses after TIV 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† Time point 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
A/H1N1 Yes Day 0 13/20 19/44
(65.0; 40.8–84.6) (43.2; 28.3–59.0)
   Day 21 20/20 41/44 13/20 31/44 20; 7.1 44; 6.8
(100; 83.2–100) (93.2; 81.3–98.6) (65.0; 40.8–84.6) (70.5; 54.8–83.2) (3.5– 14.3) (4.7–9.8)
  No Day 0 16/29 3/26
(55.2; 35.7–73.6) (11.5; 2.4–30.2)
   Day 21 29/29 21/26 22/29 19/26 29; 12.6 26; 16.0
(100; 88.1–100) (80.8; 60.6–93.4) (75.9; 56.5–89.7) (73.1; 52.2–88.4) (6.8– 23.3) (9.4–27.3)
A/H3N2 Yes Day 0 8/20 15/44
(40.0; 19.1–63.9) (34.1; 20.5–49.9)
   Day 21 20/20 43/44 15/20 35/44 20; 8.9 44; 9.9
(100; 83.2–100) (97.7; 88.0–99.9) (75.0; 50.9–91.3) (79.5; 64.7–90.2) (4.7– 16.8) (6.7–14.7)
  No Day 0 7/29 2/26
(24.1; 10.3–43.5) (7.7; 0.9–25.1)
   Day 21 28/29 22/26 26/29 22/26 29; 17.2 26; 25.8
(96.6; 82.2–99.9) (84.6; 65.1–95.6) (89.7; 72.6–97.8) (84.6; 65.1–95.6) (11.8–25.1) (15.7–42.5)
B strain (Victoria) Yes Day 0 12/20 27/44   
(60.0; 36.1–80.9) (61.4; 45.5–75.6)
   Day 21 20/20 44/44 10/20 27/44 20; 5.3 44; 5.0
(100; 83.2–100) (100; 92.0–100) (50.0; 27.2–72.8) (61.4; 45.5–75.6) (2.7– 10.4) (3.5–7.0)
  No Day 0 9/29 8/26   
(31.0; 15.3–50.8) (30.8; 14.3–51.8)
   Day 21 27/29 25/26 23/29 24/26 29; 19.6 26; 23.9
(93.1; 77.2–99.2) (96.2; 80.4–99.9) (79.3; 60.3–92.0) (92.3; 74.9–99.1) (10.3– 37.2) (14.0–40.6)
  1. †Received (yes) or did not receive (no) seasonal influenza vaccine during the preceding 3 seasons (2009–2010, 2008–2009, 2007–2008); n/N, number fulfilling definition of response/total number in group; TIV, inactivated trivalent influenza vaccine; 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].