Table 3.
Percentages of subjects (95% CI) achieving seroconversion in HI titer a.
| Age 18 to <65 Years | Age ≥65 Years | Total Population | ||||
|---|---|---|---|---|---|---|
| aH5N1c | Placebo | aH5N1c | Placebo | aH5N1c | Placebo | |
| Day 22, n | 1115 | 370 | 1130 | 366 | 2245 | 736 |
| Seroconversion, % (95% CI) | 40.4 (37.6–43.4) |
1.9 (0.8–3.9) |
24.2 (21.7–26.8) |
0.3 (0.0–1.5) |
32.2 (30.3–34.2) |
1.1 (0.5–2.1) |
| Day 43, n | 1076 | 349 | 1080 | 351 | 2156 | 700 |
| Seroconversion, % (95% CI) | 79.9 (77.4–82.3) |
0.3 (0.0–1.6) |
54.0 (51.0–57.0) |
1.7 (0.6–3.7) |
66.9 (64.9–68.9) |
1.0 (0.4–2.0) |
| Day 183, n | 1025 | 341 | 1054 | 346 | 2079 | 687 |
| Seroconversion, % (95% CI) | 16.2 (14.0–18.6) |
0.3 (0.0–1.6) |
8.0 (6.4–9.8) |
1.2 (0.3–2.9) |
12.0 (10.7–13.5) |
0.7 (0.2–1.7) |
Abbreviations: CBER, Center for Biologics Evaluation and Research; CI, confidence interval; HI, hemagglutination inhibition. a Seroconversion was defined as either a prevaccination (baseline) HI titer <1:10 and postvaccination HI titer ≥1:40 or a prevaccination HI titer ≥1:10 and a ≥4-fold increase in postvaccination HI antibody titer. Boldface indicates CBER criteria for seroconversion were met, i.e., lower bound of 95% CI ≥40% for subjects younger than 65 years and ≥30% for subjects aged ≥65 years on Day 43.