Table 2.
Hemagglutination Inhibition (HAI) Assay: Geometric Mean Titers (GMT) and Geometric Mean Fold Rise (GMFR) in the According-to-Protocol Immunogenicity Cohort (Day 42) and the Day 182 Immunogenicity Set
| HAI GMT n (95% CI) |
HAI GMFR n (95% CI) |
|||||
| Age | Treatment group | Prevaccinationa | Day 42 | Day 182 | Day 42 | Day 182 |
| 18–64 years | Vaccine | 1571 5.0 (5.0–5.0) | 1571 249.0 (231.8–267.5) | 366 36.2 (31.0–42.2) | 1571 49.6 (46.2–53.3) | 366 7.2 (6.2–8.4) |
| Placebo | 76 5.0 (5.0–5.0) | 76 5.1 (4.9–5.4) | 37 5.5 (4.8–6.5) | 76 1.0 (1.0–1.1) | 37 1.1 (1.0–1.3) | |
| ≥65 years | Vaccine | 396 5.2 (5.1–5.3) | 396 81.9 (69.7–96.2) | 91 44.8 (33.3–60.4) | 396 15.8 (13.4–18.5) | 91 8.8 (6.5–11.9) |
| Placebo | 40 5.0–(5.0–5.0) | 40 5.5 (4.5–6.8) | 19 5.4 (4.6–6.3) | 40 1.1 (0.9–1.4) | 19 1.1 (0.9–1.3) | |
| 18–60 years | Vaccine | 1488 5.0 (5.0–5.0) | 1488 258.0 (239.7–277.7) | 353 37.5 (31.8–43.6) | 1488 51.4 (47.8–55.3) | 353 7.4 (6.3–8.7) |
| Placebo | 68 5.0 (5.0–5.0) | 68 5.2 (4.9–5.5) | 29 5.7 (4.7–6.9) | 68 1.0 (1.0–1.1) | 29 1.1 (0.9–1.4) | |
| ≥61 years | Vaccine | 479 5.2 (5.0–5.3) | 479 89.0 (77.1–102.7) | 104 39.6 (29.9–52.5) | 479 17.2 (14.9–19.9) | 104 7.8 (5.9–10.4) |
| Placebo | 48 5.0 (5.0–5.0) | 48 5.5 (4.6–6.5) | 27 5.3 (4.7–5.8) | 48 1.1 (0.9–1.3) | 27 1.1 (0.9–1.2) | |
| ≥75 years | Vaccine | 119 5.1 (5.0–5.2) | 119 75.2 (55.7–101.5) | 22 45.4 (25.2–81.8) | 119 14.8 (11.0–20.0) | 22 9.1 (5.0–16.4) |
| Placebo | 12 5.0 (5.0–5.0) | 12 7.1 (3.3–15.2) | 4 5.0 (5.0–5.0) | 12 1.4 (0.7–3.0) | 4 1.0 (1.0–1.0) | |
NOTE. GMFR is defined as the mean of the within-subject ratios of pre- and postvaccination reciprocal HAI titers; to fulfill the European licensure criterion, GMFR >2.5 (18–60 years of age) and >2.0 (≥61 years of age); there was no US criterion for GMFR. CI, confidence interval.
a
According-to-protocol immunogenicity cohort.