Table 2.
HAI antibody responses.
| A/H1N1 |
A/H3N2 |
B Victoria lineage |
B Yamagata lineage |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Age | Measure | Day | Pooled IIV4 | Pooled IIV3 | Pooled IIV4 | Pooled IIV3 | Pooled IIV4 | IIV3-1 | Pooled IIV4 | IIV3-2 |
| 18–60 y | N | — | 833 | 278 | 832 | 278 | 832 | 140 | 832 | 138 |
| GMT (95% CI) | 0 | 62.2 (55.6; 69.7) | 66.7 (54.9; 80.9) | 48.6 (43.3; 54.4) | 42.2 (34.8; 51.0) | 61.3 (55.3; 67.8) | 64.5 (50.1; 83.0) | 233 (210; 259) | 285 (222; 365) | |
| 21 | 608 (563; 657) | 685 (587; 800) | 498 (459; 541) | 629 (543; 728) | 708 (661; 760) | 735 (615; 879) | 1715 (1607; 1830) | 1735 (1490; 2019) | ||
| Seroprotectiona, % (95% CI) | 0 | 64.6 (61.2; 67.8) | 68.3 (62.5; 73.8) | 58.5 (55.1; 61.9) | 55.8 (49.7; 61.7) | 61.9 (58.5; 65.2) | 67.9 (59.4; 75.5) | 88.0 (85.6; 90.1) | 90.6 (84.4; 94.9) | |
| 21 | 98.2 (97.0; 99.0) | 97.1 (94.4; 98.7) | 98.0 (96.7; 98.8) | 98.6 (96.4; 99.6) | 99.8 (99.1; 100.0) | 100.0 (97.4; 100.0) | 100.0 (99.6; 100.0) | 100.0 (97.4; 100.0) | ||
| GMTR (95% CI) | 21/0 | 9.77 (8.69; 11.0) | 10.3 (8.35; 12.7) | 10.3 (9.15; 11.5) | 14.9 (12.1; 18.4) | 11.6 (10.4; 12.9) | 11.4 (8.66; 15.0) | 7.35 (6.66; 8.12) | 6.08 (4.79; 7.72) | |
| Seroconversion or significant increase, % (95% CI) | 21/0 | 64.1 (60.7; 67.4) | 65.1 (59.2; 70.7) | 66.2 (62.9; 69.4) | 73.4 (67.8; 78.5) | 70.9 (67.7; 74.0) | 70.0 (61.7; 77.4) | 63.7 (60.3; 67.0) | 60.9 (52.2; 69.1) | |
| >60 y | N | — | 832 | 275 | 831 | 274 | 831 | 138 | 831 | 137 |
| GMT (95% CI) | 0 | 44.3 (39.9; 49.2) | 44.4 (36.7; 53.6) | 64.1 (57.3; 71.7) | 70.8 (57.8; 86.7) | 62.2 (56.2; 68.9) | 65.4 (51.1; 83.7) | 159 (145; 175) | 170 (132; 217) | |
| 21 | 219 (199; 241) | 268 (228; 314) | 359 (329; 391) | 410 (352; 476) | 287 (265; 311) | 301 (244; 372) | 655 (611; 701) | 697 (593; 820) | ||
| Seroprotectiona, % (95% CI) | 0 | 57.7 (54.3; 61.1) | 59.3 (53.2; 65.1) | 65.8 (62.5; 69.0) | 67.9 (62.0; 73.4) | 65.9 (62.6; 69.2) | 70.3 (61.9; 77.8) | 86.3 (83.8; 88.5) | 86.9 (80.0; 92.0) | |
| 21 | 90.6 (88.4; 92.5) | 94.5 (91.2; 96.9) | 96.1 (94.6; 97.4) | 97.8 (95.3; 99.2) | 96.5 (95.0; 97.7) | 95.7 (90.8; 98.4) | 100.0 (99.6; 100.0) | 100.0 (97.3; 100.0) | ||
| GMTR (95% CI) | 21/0 | 4.94 (4.46; 5.47) | 6.03 (4.93; 7.37) | 5.60 (5.02; 6.24) | 5.79 (4.74; 7.06) | 4.61 (4.18; 5.09) | 4.60 (3.50; 6.05) | 4.11 (3.73; 4.52) | 4.11 (3.19; 5.30) | |
| Seroconversion or significant increase, % (95% CI) | 21/0 | 45.6 (42.1; 49.0) | 50.2 (44.1; 56.2) | 47.5 (44.1; 51.0) | 48.5 (42.5; 54.6) | 45.2 (41.8; 48.7) | 43.5 (35.1; 52.2) | 42.7 (39.3; 46.2) | 38.7 (30.5; 47.4) | |
Values are for all participants vaccinated with available pre- and post-vaccination HAI titers. Abbreviations: CI, confidence interval; GMT, geometric mean titer; GMTR, geometric mean of the individual ratios of the post-vaccination (day 21) HAI titer divided by the pre-vaccination (day 0) HAI titer; HAI, hemagglutination inhibition; IIV3, trivalent inactivated influenza vaccine; IIV4, quadrivalent inactivated influenza vaccine.
a
Seroprotection was defined as a HAI titer ≥40.
b
Seroconversion was defined as a pre-vaccination (day 0) HAI titer <10 and a post-vaccination (day 21) HAI titer ≥1:40, and a significant increase was defined as a pre-vaccination HAI titer ≥10 and a ≥4-fold increase in HAI titer.