Table 1.
Characteristics of Study Participantsa
| Characteristic | Enrolled Patients, No. | Patients, No. (Row %) | ||
|---|---|---|---|---|
| Influenza Virus Positive | Influenza Virus Negative | Receipt of Seasonal Influenza Vaccine | ||
| Overall | 10 012 | 2763 (28) | 7249 (72) | 5381 (54) |
| Study site | ||||
| Michigan | 1817 | 477 (26) | 1340 (74) | 1138 (63) |
| Pennsylvania | 1701 | 540 (32) | 1161 (68) | 823 (48) |
| Texas | 1833 | 353 (19) | 1480 (81) | 777 (42) |
| Washington | 2692 | 778 (29) | 1914 (71) | 1620 (60) |
| Wisconsin | 1969 | 615 (31) | 1354 (69) | 1023 (52) |
| Sex | ||||
| Male | 4018 | 1224 (30) | 2794 (69) | 2061 (51) |
| Female | 5994 | 1539 (26) | 4455 (74) | 3320 (55) |
| Age group | ||||
| 6 mo to 8 y | 2428 | 751 (31) | 1677 (69) | 1278 (53) |
| 9–17 y | 1261 | 489 (39) | 772 (61) | 536 (43) |
| 18–49 y | 3256 | 821 (25) | 2435 (75) | 1397 (43) |
| 50–64 y | 1766 | 442 (25) | 1324 (75) | 1095 (62) |
| ≥65 y | 1301 | 260 (20) | 1041 (80) | 1075 (83) |
| Race/ethnicity | ||||
| White | 6845 | 1841 (27) | 5004 (73) | 3916 (57) |
| Black | 1142 | 350 (31) | 792 (69) | 419 (37) |
| Other race | 1023 | 301 (29) | 722 (71) | 558 (55) |
| Hispanic | 947 | 258 (27) | 689 (73) | 461 (49) |
aPatients with medically attended acute respiratory illness enrolled in the US Influenza Vaccine Effectiveness Network from 23 November 2018 through 3 May 2019, by influenza test result status and seasonal influenza vaccination status.