Table 4.
Descriptive Characteristics of Participants With Medically Attended Acute Respiratory Illness by Influenza Vaccination Status
| Characteristic | All Vaccinateda | Standard-Dose IIV3b | IIV4 | High-Dose IIV3 | LAIV4 | P Valuec |
|---|---|---|---|---|---|---|
| All, no. (%)d | 4360 | 1733 (39.7) | 2041 (46.8) | 69 (1.6) | 517 (11.9) | |
| Site | <.001 | |||||
| Michigan | 720 | 52 (7.2) | 550 (76.4) | 44 (6.1) | 74 (10.3) | |
| Pennsylvania | 540 | 136 (25.2) | 322 (59.6) | 8 (1.5) | 74 (13.7) | |
| Texas | 603 | 80 (13.3) | 446 (74.0) | 14 (2.3) | 63 (10.4) | |
| Washington | 1568 | 697 (44.5) | 682 (43.5) | 0 (0) | 189 (12.1) | |
| Wisconsin | 929 | 769 (82.7) | 41 (4.4) | 3 (0.3) | 117 (12.6) | |
| Age | <.001 | |||||
| 6 mo–8 y | 1191 | 340 (28.5) | 545 (45.8) | 0 (0) | 306 (25.7) | |
| 6 mo–23 mo | 309 | 128 (41.3) | 181 (58.4) | 0 (0) | 0 (0) | |
| 2–8 y | 882 | 212 (24.0) | 364 (41.2) | 0 (0) | 306 (34.7) | |
| 9–17 y | 506 | 130 (25.7) | 203 (40.1) | 0 (0) | 173 (34.2) | |
| 18–49 y | 956 | 469 (49.1) | 449 (47.0) | 1 (0.1) | 37 (3.9) | |
| 50–64 y | 791 | 418 (52.8) | 372 (47.0) | 1 (0.1) | 0 (0) | |
| ≥65 y | 916 | 376 (41.0) | 472 (51.5) | 67 (7.3) | 1 (0.1) | |
| Male | 1792 | 675 (37.7) | 840 (46.9) | 25 (1.4) | 252 (14.1) | <.001 |
| Race/ethnicitye | <.001 | |||||
| White, non-Hispanic | 3354 | 1451 (43.3) | 1472 (43.9) | 57 (1.7) | 374 (11.2) | |
| Black, non-Hispanic | 231 | 57 (24.7) | 150 (64.9) | 4 (1.7) | 20 (8.7) | |
| Hispanic | 314 | 57 (18.2) | 192 (61.1) | 6 (1.9) | 59 (18.8) | |
| Other, non-Hispanic | 426 | 135 (31.7) | 226 (53.1) | 2 (0.5) | 63 (14.8) | |
| High-risk condition | <.001 | |||||
| Any high-risk condition | 2029 | 838 (41.3) | 1070 (52.7) | 50 (2.5) | 71 (3.5) | <.001 |
| Asthma/pulmonary | 1088 | 439 (40.3) | 582 (53.5) | 14 (1.3) | 53 (4.9) | <.001 |
| Cardiovascular | 712 | 303 (42.6) | 374 (52.5) | 26 (3.7) | 9 (1.3) | <.001 |
| Diabetes | 480 | 203 (42.3) | 253 (52.7) | 22 (4.6) | 2 (0.4) | <.001 |
| Morbid obesityf | 353 | 165 (46.7) | 180 (51.0) | 3 (0.8) | 5 (1.4) | <.001 |
| Other | 824 | 375 (45.5) | 407 (49.4) | 26 (3.2) | 16 (1.9) | <.001 |
| Interval from onset to enrollment | .001 | |||||
| 0–2 d | 1294 | 486 (37.6) | 605 (46.8) | 18 (1.4) | 185 (14.3) | |
| 3–4 d | 1646 | 631 (38.3) | 790 (48.0) | 28 (1.7) | 197 (12.0) | |
| 5–7 d | 1420 | 616 (43.4) | 646 (45.5) | 23 (1.6) | 135 (9.5) | |
| Reported general health statusg | <.001 | |||||
| Excellent/very good | 3008 | 1121 (37.3) | 1390 (46.2) | 35 (1.2) | 462 (15.4) | |
| Good | 1026 | 466 (45.4) | 491 (47.9) | 24 (2.3) | 45 (4.4) | |
| Fair/poor | 320 | 145 (45.3) | 156 (48.8) | 10 (3.1) | 9 (2.8) | |
| Self/household exposure to smokeh | 519 | 242 (46.6) | 207 (39.9) | 2 (0.4) | 68 (13.1) | <.001 |
| Number of children aged <12 y in householdi | <.001 | |||||
| 0 | 2766 | 1199 (43.3) | 1320 (47.7) | 66 (2.4) | 181 (6.5) | |
| 1 | 965 | 311 (32.2) | 444 (46.0) | 3 (0.3) | 207 (21.5) | |
| ≥2 | 628 | 222 (35.4) | 277 (44.1) | 0 (0) | 129 (20.5) | |
| Reported current health assessment, median (interquartile range)j | <.001 | |||||
| Scale 1 (worst) – 100 (best) | 60 (45–75) | 55 (40–70) | 60 (45–75) | 60 (45–70) | 65 (50–75) | |
| Reverse transcription polymerase chain reaction–confirmed Influenza status | .19 | |||||
| Positive | 941 | 388 (41.2) | 413 (43.9) | 17 (1.8) | 123 (13.1) | |
| Negative | 3419 | 1345 (39.3) | 1628 (47.6) | 52 (1.5) | 394 (11.5) |
The interquartile range represents the 25th–75th percentile.
Abbreviations: IIV, inactivated influenza vaccine; IIV3, trivalent inactivated influenza vaccine; IIV4, quadrivalent inactivated influenza vaccine; LAIV, live attenuated influenza vaccine.
a Defined as having ≥1 dose of any influenza vaccine ≥14 days before illness onset. Excludes 604 participants who received a vaccine of undetermined type.
b Among those who received standard-dose IIV3, 9 were cell culture IIV3 and 1 was intradermal.
c The χ2 test statistic was used to assess differences by vaccine type received, with respect to the distributions of site, age group, sex, race/ethnicity, presence of high-risk conditions, interval from illness onset to enrollment, general health status, self/household smoke exposure, number of children <12 in the household, and reverse transcription polymerase chain reaction–confirmed influenza positivity. The Kruskal–Wallis test was used to assess differences with respect to the distribution of the current health assessment. P < .05 is statistically significant and bolded.
d Data are presented as no. (row %).
e Data on race/ethnicity were missing for 5 participants.
f Morbid obesity was defined as a body mass index ≥40 kg/m2 at enrollment or at least 1 International Classification of Diseases, 9th Edition, Clinical Modification code for morbid obesity in the year prior to enrollment.
g Data on general health status were missing for 6 participants.
h Data on exposure to smoke were missing for 5 participants.
i Data on children aged <12 years in the household were missing for 1 participant.
j Data on current health assessment were missing for 6 participants.