Table 3.
Seroprotection and Seroconversion, Based on Hemagglutination Inhibition (HI) Findings at Days 0, 30, and 180, for Recipients of Standard-Dose and High-Dose Influenza Vaccines, by Influenza Season and Vaccine Strain
| Season, Serostatus and Time(s), Strain | Overall, Subjects, No. (%) | Randomized Group, Subjects, No. (%) |
P valuea | |
|---|---|---|---|---|
| Standard Dose | High Dose | |||
| 2011–2012 | ||||
| Seroprotection, day 0 | n = 64 | n = 33 | n = 31 | |
| A/California/07/2009(H1N1) | 22 (34.4) | 12 (36.4) | 10 (32.3) | .73 |
| A/Victoria/210/2009(H3N2) | 4 (6.3) | 2 (6.1) | 2 (6.5) | .95 |
| B/Brisbane/60/2008 | 13 (20.3) | 5 (15.2) | 8 (25.8) | .29 |
| Seroprotection, day 30 | n = 64 | n = 33 | n = 31 | |
| A/California/07/2009(H1N1) | 39 (60.9) | 17 (51.5) | 22 (71.0) | .11 |
| A/Victoria/210/2009(H3N2) | 20 (31.3) | 6 (18.2) | 14 (45.2) | .02 |
| B/Brisbane/60/2008 | 21 (32.8) | 7 (21.2) | 14 (45.2) | .04 |
| Seroprotection, day 180b | n = 50 | n = 24 | n = 26 | |
| A/California/07/2009(H1N1) | 31 (62.0) | 11 (45.8) | 20 (76.9) | .02 |
| A/Victoria/210/2009(H3N2) | 14 (28.0) | 3 (12.5) | 11 (42.3) | .02 |
| B/Brisbane/60/2008 | 7 (14.0) | 1 (4.2) | 6 (23.1) | .10 |
| Seroconversion, day 30/day 0 | n = 64 | n = 33 | n = 31 | |
| A/California/07/2009(H1N1) | 25 (39.1) | 7 (21.2) | 18 (58.1) | <.01 |
| A/Victoria/210/2009(H3N2) | 12 (18.8) | 3 (9.1) | 9 (29.0) | .04 |
| B/Brisbane/60/2008 | 5 (7.8) | 0 (0.0) | 5 (16.1) | .02 |
| 2012–2013 | ||||
| Seroprotection, day 0 | n = 123 | n = 65 | n = 58 | |
| A/California/07/2009(H1N1) | 61 (49.6) | 35 (53.8) | 26 (44.8) | .32 |
| A/Victoria/361/2011(H3N2) | 5 (4.1) | 3 (4.6) | 2 (3.4) | .74 |
| B/Texas/6/2011 | 9 (7.3) | 4 (6.2) | 5 (8.6) | .60 |
| Seroprotection, day 30 | n = 123 | n = 65 | n = 58 | |
| A/California/07/2009(H1N1) | 81 (65.9) | 47 (72.3) | 34 (58.6) | .11 |
| A/Victoria/361/2011(H3N2) | 46 (37.4) | 16 (24.6) | 30 (51.7) | <.01 |
| B/Texas/6/2011 | 47 (38.2) | 19 (29.2) | 28 (48.3) | .03 |
| Seroprotection day 180b | n = 112 | n = 59 | n = 53 | |
| A/California/07/2009(H1N1) | 56 (50.0) | 31 (52.5) | 25 (47.2) | .57 |
| A/Victoria/361/2011(H3N2) | 51 (45.5) | 23 (39.0) | 28 (52.8) | .14 |
| B/Texas/6/2011 | 37 (33.0) | 20 (33.9) | 17 (32.1) | .84 |
| Seroconversion, day 30/day 0 | n = 123 | n = 65 | n = 58 | |
| A/California/07/2009(H1N1) | 21 (17.1) | 7 (10.8) | 14 (24.1) | <.05 |
| A/Victoria/361/2011(H3N2) | 40 (32.5) | 13 (20.0) | 27 (46.6) | <.01 |
| B/Texas/6/2011 | 35 (28.5) | 11 (16.9) | 24 (41.4) | <.01 |
Seroprotection was defined as a hemagglutination inhibition (HI) titer of ≥40. Seroconversion was defined as a day 30 HI titer of ≥40 and a 4-fold increase from the day 0 HI titer.
a By the χ2 test.
b Six participants in the standard-dose group and 5 in the high-dose group died before collection of blood samples at day 180.