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Table 1 Immune response for haemagglutination-inhibition (HI) antibodies against A/California/7/2009 H1N1 in adults aged 18 to 60 years and in adults >60 years (per-protocol immunogenicity cohorts)

From: Flexibility of interval between vaccinations with AS03A-adjuvanted influenza A (H1N1) 2009 vaccine in adults aged 18–60 and >60 years: a randomized trial

  N Seroprotection rate (titre ≥ 1:40) % (95% CI) Seroconversion rate* % (95% CI) Geometric Mean Fold Rise** (95% CI) N Seroprotection rate (titre ≥ 1:40) % (95% CI) Seroconversion rate* % (95% CI) Geometric Mean Fold Rise** (95% CI)
   Vaccinated on Day 0 (subjects from Groups A and B pooled) 18–60 years   Vaccinated on Day 0 (subjects from Groups A and B pooled) 18>60 years
Day 0 (Prevaccination) 160 14.4 - - 136 5.1 - -
(9.3-20.8)     (2.1-10.3)   
Day 21 160 97.5 96.3 45.0 136 91.9 89.0 23.4
(93.7-99.3) (92.0-98.6) (37.3-54.5)   (86.0-95.9) (82.5-93.7) (19.1-28.7)
  Group A Vaccinated on Day 0 and Day 21 1860 years Group A Vaccinated on Day 0 and Day 21 >60 years
Day 0 (Prevaccination) 87 12.6 - - 83 7.2 - -
(6.5-21.5)   -   (2.7-15.1)   
Day 21 87 100 100 51.6 83 90.4 89.2 23.0
(95.8-100) (95.8-100) (40.7-65.5)   (81.9-95.7) (80.4-94.9) (17.7-29.9)
Day 42 87 100 98.9 86.7 83 100 98.8 54.9
(95.8-100) (93.8-100) (68.6-109.5)   (95.7-100) (93.5-100) (43.4-69.3)
Day 182 85 97.6 92.9 26.6 83 90.4 86.7 13.4
(91.8-99.7) (85.3-97.4) (20.8-34.0)   (81.9-95.7) (77.5-93.2) (10.9-16.5)
Day 203   - - -   - - -
Day 364 79 82.3 75.9 11.0 76 50.0 40.8 4.8
(72.1-90.0) (65.0-84.9) (9.2-15.5)   (38.3-61.7) (29.6-52.7) (3.8-6.1)
  Group B Vaccinated on Day 0 and Day 182 1860 years Group B Vaccinated on Day 0 and Day 182 >60 years
Day 0 (Prevaccination 67 14.9 (7.4-25.7) - - 48 2.1 (0.1-11.1) - -
Day 21 67 94.0 92.5 39.2 48 95.8 89.6 23.3
(85.4-98.3) (83.4-97.5) (28.3-54.2)   (85.7-99.5) (77.3-96.5) (16.6-32.7)
Day 42 67 95.5 91.0 31.9 48 89.6 81.3 16.5
(87.5-99.1) (81.5-96.6) (23.4-43.4)   (77.3-96.5) (67.4-91.1) (11.8-23.0)
Day 182 56 85.7 83.9 14.6 30 63.3 56.7 6.1
(73.8-93.6) (71.7-92.4) (10.8-19.7)   (43.9-80.1) (37.4-74.5) (3.9-9.4)
Day 203 48 100 100 79.0 28 100 100 65.7
(92.6-100) (92.6-100) (58.0-107.7)   (87.7-100) (87.7-100) (41.4-104.1)
Day 364 60 93.3 90.0 17.3 46 80.4 73.9 8.3
(83.8-98.2) (79.5-96.2) (13.0-23.0)   (66.1-90.6) (58.9-85.7) (6.0-11.3)
  1. *Seroconversion rate for haemagglutination-inhibition antibody response is defined as the percentage of vaccinees who have a prevaccination titre <1:10 and a post-vaccination titre ≥1:40, or a significant increase in antibody titre defined as the percentage of vaccinees who have a pre-vaccination titre ≥ 1:10 and at least a fourfold increase in post-vaccination titre. **Geometric mean fold rise is defined as geometric mean of the within-subject ratios of the post-vaccination reciprocal haemagglutination-inhibition titre to the Day 0 reciprocal agglutination-inhibition titre.
  2. European Medicines Agency Committee for Medicinal Products for Human Use (CHMP) criteria for haemagglutination-inhibition antibody response in 18–60 year olds are: seroprotection rate >70%, seroconversion rate >40%, and geometric mean fold rise >2·5 and in adults >60 years are seroprotection rate >60%, seroconversion rate >30%, and geometric mean fold rise >2·0.
  3. United States Center for Biologics Evaluation and Research (CBER) criteria for hemagglutination-inhibition antibody response in adults <65 years are: lower limit (LL) of 95% CI for seroprotection ≥70% and LL of 95% CI for seroconversion ≥40% and in adults ≥65 years are LL of 95% CI for seroprotection ≥60% and LL of 95% CI for seroconversion ≥30%.