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Table 3 Comparison of immunogenicity results after intradermal or intramuscular vaccination

From: Intradermal influenza vaccination of healthy adults using a new microinjection system: a 3-year randomised controlled safety and immunogenicity trial

Vaccine received in Year 1   3 μg ID 6 μg ID 15 μg IM 3 μg ID 6 μg ID 15 μg IM 3 μg ID 6 μg ID 15 μg IM
  European Medicines Evaluation Agency criteria A/H1N1 A/H3N2 B
Geometric mean titre (95% CI) - 93.6 (78.5;112) 110 (90.5;133) 206 (177;239) 132 (117;149) 156 (137;178) 300 (266;337) 19.2 (17.1;21.5) 21.7 (19.3;24.5) 40.8 (36.1;46.2)
Seroprotection rate*, % (95% CI) >70 72.7 (67.9;77.1) 71.3 (66.5;75.8) 87.1 (83.3;90.3) 88.5 (84.9;91.5) 88.2 (84.5;91.3) 96.9 (94.6;98.4) 28.5 (23.9;33.3) 32.9 (28.1;37.9) 55.7 (50.5;60.8)
Seroconversion/significant increase rate, % (95% CI) >40 53.1 (48.0;58.2) 55.1 (50.0;60.1) 75.0 (70.3;79.3) 35.4 (30.6;40.4) 43.0 (38.0;48.2) 63.8 (58.7;68.6) 21.0 (17.0;25.5) 27.3 (22.8;32.1) 47.7 (42.6;52.9)
Geometric mean titre ratio (post-/pre-vaccination) (95% CI) 2.5 7.32 (6.16;8.7) 8.38 (6.94;10.1) 17.4 (14.7;20.5) 3.48 (3.02;4.01) 4.19 (3.58;4.90) 9.11 (7.71;10.8) 2.38 (2.13;2.67) 2.73 (2.42;3.07) 4.97 (4.37;5.67)
Vaccine received in Year 2   9 μg ID 15 μg IM 9 μg ID 15 μg IM 9 μg ID 15 μg IM
Geometric mean titre (95% CI) - 180 (161; 202) 192 (174; 212) 380 (343; 420) 386 (355; 420) 80.6 (71.6; 90.7) 83.1 (74.8; 92.3)
Seroprotection rate*, % (95% CI) >70 90.0 (87.1; 92.4) 93.4 (90.0; 95.3) 97.2 (95.4; 98.4) 99.4 (98.4; 99.9) 73.0 (69.1; 76.8) 74.4 (70.5; 78.0)
Seroconversion/significant increase rate, % (95% CI) >40 43.0 (38.8; 47.3) 45.7 (41.4; 50.0) 53.1 (48.8; 57.4) 50.8 (46.5; 55.1) 63.4 (59.2; 67.5) 66.6 (62.5; 70.6)
Geometric mean titre ratio (post-/pre-vaccination) (95% CI) 2.5 4.3 (3.8; 4.8) 4.7 (4.2; 5.3) 4.4 (4.0; 5.0) 4.4 (3.9; 5.0) 7.8 (7.0; 8.8) 8.3 (7.5; 9.1)
Vaccine received in Year 3   9 μgID 15 μgIM 9 μgID 15 μgIM 9 μgID 15 μgIM
Geometric mean titre (95% CI) - 127 (103; 158) 117.8 (92.7; 149.6) 415 (337; 510) 300 (242; 373) 91.0 (74.5; 111.1) 86.2 (68.4; 108.7)
Seroprotection rate*, % (95% CI) >70 90.7 (83.6; 95.5) 91.3 (84.2; 96.0) 100 (96.6; 100) 99.0 (94.8; 100.0) 83.3 (74.9; 89.8) 81.4 (72.4; 88.4)
Seroconversion/significant increase rate, % (95% CI) >40 14.8 (8.7; 22.9) 18.3 (11.4; 27.1) 60.2 (50.3; 69.5) 45.2 (35.4; 55.3) 24.1 (16.4; 33.3) 19.6 (12.4; 28.6)
Geometric mean titre ratio (post-/pre-vaccination) (95% CI) 2.5 2.0 (1.7; 2.4) 2.1 (1.7; 2.5) 4.6 (3.8; 5.6) 3.5 (2.8; 4.4) 2.3 (1.9; 2.7) 2.3 (1.9; 2.8)
  1. CI, confidence interval; ID, intradermal; IM, intramuscular.
  2. *Defined as antibody titre ≥ 40; for subjects with a titre <10 on day 0, defined as a post-injection titre ≥ 40; for subjects with a titre ≥ 10 on day 0, defined as a ≥ 4-fold increase in titres. Data are from the other immunogenicity (OI) population.