Table 3.
Immunogenicity: Geometric Mean Titer of Reenrolled Participants by Hemagglutination Inhibition Assay
| Influenza Type/Subtype | Vaccination Patterna |
||||
|---|---|---|---|---|---|
| Y1 IIV-HD, Y2 IIV-HD (n = 643) | Y1 IIV-SD, Y2 IIV-HD (n = 605) | Y1 IIV-HD or IIV-SD, Y2 IIV-HD (n = 1248) | Y1 IIV-HD, Y2 IIV-SD (n = 639) | Y1 IIV-SD, Y2 IIV-SD (n = 617) | |
| A(H1N1) | 322.1 (295.0–351.6) | 416.7 (382.6–453.9) | 364.9 (343.1–388.1) | 207.9 (188.2–229.7) | 198.6 (180.1–219.1) |
| A(H3N2) | 400.6 (366.7–437.7) | 459.3 (419.1–503.4) | 428.1 (401.7–456.2) | 242.4 (220.6–266.4) | 243.0 (220.8–267.5) |
| B | 88.2 (81.1–95.8) | 93.2 (85.8–101.2) | 90.5 (85.4–96.0) | 52.3 (48.2–56.7) | 57.9 (53.3–62.8) |
Data are presented as geometric mean titer (95% confidence interval), calculated using the t distribution applied to log-transformed titers. The n values represent reenrolled subjects in the immunogenicity subset with assay results. Samples were obtained approximately 28 days after year 2 vaccination.
Abbreviations: IIV-HD, high-dose inactivated influenza vaccine; IIV-SD, standard-dose inactivated influenza vaccine; Y1, year 1; Y2, year 2.
a Based on vaccine assigned on randomization in Y2, and vaccine actually received in Y1.