Table 1.
Descriptive Characteristics of Enrolled Patients With Medically Attended Acute Respiratory Illness, by Case Status
| Characteristic | Any Influenza Virus Detecteda,b,c,d,e (n = 2307) | Influenza A(H3N2) Detectedb,c (n = 1292) | Influenza B/Yamagata Detectedc,d,e (n = 582) | Influenza B/Victoria Detectede (n = 303) | No Influenza Virus Detected (n = 4145) |
|---|---|---|---|---|---|
| Site | |||||
| Michigan | 527 (23) | 255 (20) | 232 (40) | 19 (6) | 781 (19) |
| Pennsylvania | 371 (16) | 267 (21) | 48 (8) | 28 (9) | 752 (18) |
| Texas | 432 (19) | 220 (17) | 154 (26) | 43 (14) | 930 (22) |
| Washington | 219 (9) | 174 (13) | 6 (1) | 6 (2) | 913 (22) |
| Wisconsin | 758 (33) | 376 (29) | 142 (24) | 207 (68) | 769 (19) |
| Age | |||||
| 6 mo–8 y | 555 (24) | 242 (19) | 177 (30) | 118 (39) | 954 (23) |
| 9–17 y | 420 (18) | 178 (14) | 146 (25) | 72 (24) | 561 (14) |
| 18–49 y | 739 (32) | 478 (37) | 143 (25) | 73 (24) | 1528 (37) |
| 50–64 y | 370 (16) | 228 (18) | 91 (16) | 20 (7) | 670 (16) |
| ≥65 y | 223 (10) | 166 (13) | 25 (4) | 20 (7) | 432 (10) |
| Sex | |||||
| Female | 1290 (56) | 752 (58) | 293 (50) | 161 (53) | 2508 (61) |
| Male | 1017 (44) | 540 (42) | 289 (50) | 142 (47) | 1637 (39) |
| Race/ethnicity | |||||
| White, non-Hispanic | 1754 (76) | 1006 (78) | 387 (66) | 256 (84) | 3112 (75) |
| Black, non-Hispanic | 189 (8) | 94 (7) | 80 (14) | 5 (2) | 323 (8) |
| Hispanic | 175 (8) | 83 (6) | 58 (10) | 28 (9) | 366 (9) |
| Other, non-Hispanic | 185 (8) | 106 (8) | 56 (10) | 14 (5) | 335 (8) |
| Unknown | 4 (0.1) | 3 (0.2) | 1 (0.2) | 0 | 9 (0.2) |
| High-risk conditionf | |||||
| Any | 737 (32) | 467 (36) | 163 (28) | 76 (25) | 1452 (35) |
| Asthma/pulmonary | 387 (17) | 243 (19) | 79 (14) | 48 (16) | 872 (21) |
| Cardiovascular | 202 (9) | 146 (11) | 32 (6) | 13 (4) | 409 (10) |
| Diabetes | 168 (7) | 113 (9) | 33 (6) | 16 (5) | 310 (7) |
| Other | 232 (10) | 150 (12) | 51 (9) | 18 (6) | 469 (11) |
| None | 1570 (68) | 825 (64) | 419 (72) | 227 (75) | 2693 (65) |
| Morbid obesity, BMI ≥40 | |||||
| Yes | 153 (7) | 102 (8) | 31 (5) | 12 (4) | 281 (7) |
| No | 2077 (90) | 1147 (89) | 527 (91) | 288 (95) | 3678 (89) |
| Missing | 77 (3) | 43 (3) | 24 (4) | 3 (1) | 186 (4) |
| Influenza vaccination status | |||||
| 2012–2013g | |||||
| Received IIV3 | 667 (29) | 444 (34) | 111 (19) | 83 (27) | 1735 (42) |
| Received LAIV | 65 (3) | 29 (2) | 19 (3) | 10 (3) | 157 (4) |
| Received other/unknown type | 63 (3) | 45 (3) | 8 (1) | 5 (2) | 190 (5) |
| None | 1512 (66) | 774 (60) | 444 (76) | 205 (68) | 2063 (50) |
| 2011–2012h | |||||
| Received any | 808 (35) | 500 (39) | 164 (28) | 104 (34) | 1860 (45) |
| Received none | 1499 (65) | 792 (61) | 418 (72) | 199 (66) | 2285 (55) |
| Interval from onset to enrollment | |||||
| <3 d | 977 (42) | 565 (44) | 245 (42) | 119 (39) | 1354 (33) |
| 3–4 d | 912 (40) | 498 (39) | 232 (40) | 126 (42) | 1728 (42) |
| 5–7 d | 418 (18) | 229 (18) | 105 (18) | 58 (19) | 1063 (26) |
| Reported general health status | |||||
| Excellent | 903 (39) | 455 (35) | 256 (44) | 143 (47) | 1336 (32) |
| Very good | 801 (35) | 458 (35) | 202 (35) | 100 (33) | 1510 (36) |
| Good | 479 (21) | 301 (23) | 100 (17) | 45 (15) | 986 (24) |
| Fair/poor | 124 (5) | 78 (6) | 24 (4) | 15 (5) | 309 (7) |
| Missing | 0 | 0 | 0 | 0 | 4 (0.1) |
| Household exposure to smoke | |||||
| Yes | 250 (11) | 142 (11) | 62 (11) | 37 (12) | 464 (11) |
| No | 2042 (89) | 1141 (88) | 516 (89) | 264 (87) | 3665 (88) |
| Missing | 15 (0.7) | 9 (0.7) | 4 (0.7) | 2 (0.7) | 16 (0.4) |
| Household members, no. | 4 (2–5) | 3 (2–4) | 4 (3–5) | 4 (3–5) | 3 (2–4) |
| Children aged <12 y in household, no. | |||||
| 0 | 1075 (47) | 709 (55) | 199 (34) | 95 (31) | 2146 (52) |
| 1 | 499 (22) | 243 (19) | 166 (29) | 67 (22) | 877 (21) |
| ≥2 | 733 (32) | 340 (26) | 217 (37) | 141 (47) | 1122 (27) |
| Reported current health assessmenti | 50 (40–70) | 50 (40–70) | 50 (40–70) | 50 (40–70) | 60 (45–75) |
Data are no. (%) of patients or median value (interquartile range).
Abbreviations: ACIP, Advisory Committee on Immunization Practices; BMI, body mass index; IIV3, trivalent inactivated influenza vaccine; LAIV, trivalent live attenuated influenza vaccine.
a Includes 52 cases infected with 2009 pandemic influenza A(H1N1), 36 infected with influenza A for which subtype data were not available, and 50 infected with influenza B for which lineage data were not available.
b Includes 5 cases coinfected with influenza A(H3N2) and influenza B/Yamagata.
c Includes 1 case coinfected with influenza A(H3N2) and influenza B (lineage not available).
d Includes 1 case coinfected with influenza A (subtype not available) and influenza B/Yamagata.
e Includes 3 cases coinfected with influenza B/Yamagata and influenza B/Victoria.
f Presence of ≥1 medical-record-documented high-risk codes in prior year, as defined by the ACIP guidance for conditions that increase the risk for complications from influenza.
g Medical record and/or immunization registry documentation of receipt of ≥1 dose of 2012–2013 influenza vaccine (for persons aged ≥9 years) or receipt of the number of doses of 2012–13 influenza vaccine recommended by the ACIP (for persons aged 6 months through 8 years) ≥14 days before illness onset.
h Medical record and/or immunization registry documentation of receipt of ≥1 dose of 2011–2012 influenza vaccine.
i The validated EQ-5D health ruler [21] was used to assess patient health on the day of enrollment. Data are presented on a scale of 1 (worst) to 100 (best).