Table 1. Clinical characteristics of ILI patients from week 40, 2011 through week 22, 2012.
| Total | Hospital A (Seoul) | Hospital B (Seoul) | Hospital C (Suwon) | Hospital D (Ansan) | Hospital E (Wonju) | Hospital F (Incheon) | Hospital G (Cheongju) | |
| Number of patients | 1,983 | 290 | 77 | 735 | 281 | 44 | 80 | 476 |
| Sex (male), n(%) | 811 (40.9) | 111 (38.3) | 30 (39.0) | 298 (40.5) | 118 (42.0) | 23 (52.3) | 34 (42.5) | 197 (41.4) |
| Age, median (IQR) | 43 (31–63) | 35.5 (29–55) | 36 (31–55) | 46 (32–63) | 37 (30–54) | 49 (32–67) | 41.5 (33–57.5) | 53 (33–72) |
| 18–30 | 461 (23.2) | 91 (31.4) | 18 (23.4) | 154 (21.0) | 75 (26.7) | 9 (20.5) | 15 (18.8) | 99 (20.8) |
| 31–49 | 672 (33.9) | 106 (36.6) | 35 (45.5) | 251 (34.1) | 119 (42.3) | 13 (29.5) | 34 (42.5) | 114 (23.9) |
| 50–64 | 390 (19.7) | 56 (19.3) | 11 (14.3) | 157 (21.4) | 49 (17.4) | 7 (15.9) | 17 (21.3) | 93 (19.5) |
| ≥65 | 460 (23.2) | 37 (12.8) | 13 (16.9) | 173 (23.5) | 38 (13.5) | 15 (34.1) | 14 (17.5) | 170 (35.7) |
| Comorbidities | ||||||||
| unknown | 685 (34.5) | 203 (70.0) | – | 9 (1.2) | – | – | 1 (1.3) | 472 (99.2) |
| none | 942 (47.5) | 49 (16.9) | 62 (80.5) | 533 (72.5) | 216 (76.9) | 29 (65.9) | 53 (66.3) | – |
| yes | 356 (18.0) | 38 (13.1) | 15 (19.5) | 193 (26.3) | 65 (23.1) | 15 (34.1) | 26 (32.5) | 4 (0.8) |
| DM | 131 (36.8) | 10 (26.3) | 5 (33.3) | 83 (43.0) | 21 (32.3) | 4 (26.7) | 5 (19.2) | 3 (75.0) |
| Cardiovascular disease | 45 (12.6) | 7 (18.4) | 3 (20.0) | 21 (10.9) | 8 (12.3) | 3 (20.0) | 2 (7.7) | 1 (25.0) |
| Cerebrovascular disease | 52 (14.6) | 6 (15.8) | 1 (6.7) | 32 (16.6) | 4 (6.2) | 3 (20.0) | 6 (23.1) | – |
| Neuromuscular disease | 7 (2.0) | 3 (7.9) | – | 2 (1.0) | 1 (1.5) | – | 1 (3.8) | – |
| Chronic lung disease | 66 (18.5) | 5 (13.2) | 4 (26.7) | 37 (19.2) | 12 (18.5) | 6 (40.0) | 2 (7.7) | – |
| Chronic kidney disease | 25 (7.0) | 2 (5.3) | 1 (6.7) | 18 (9.3) | 2 (3.1) | – | 2 (7.7) | – |
| Chronic liver disease | 25 (7.0) | 2 (5.3) | – | 7 (3.6) | 13 (20.0) | 1 (6.7) | 2 (7.7) | – |
| Solid malignancy | 55 (15.4) | 7 (18.4) | 2 (13.3) | 25 (13.0) | 12 (18.5) | 3 (20.0) | 6 (23.1) | – |
| Hematologic malignancy | 6 (1.7) | – | 1 (6.7) | 3 (1.6) | 1 (1.5) | – | 1 (3.8) | – |
| BM transplantation | 1 (0.3) | – | – | 1 (0.5) | – | – | – | – |
| Organ transplantation | 2 (0.6) | 1 (2.6) | – | – | 1 (1.5) | – | – | – |
| Autoimmune disease | 14 (3.9) | 3 (7.9) | – | 9 (4.7) | 2 (3.1) | – | – | – |
| Pregnancy | 32 (9.0) | 7 (18.4) | 1 (6.7) | 9 (4.7) | 12 (18.5) | 1 (6.7) | 1 (3.8) | 1 (25.0) |
| ILI symptoms | ||||||||
| Fever (°C) | 38.3 (37.9–38.8) | 38.5 (38.2–38.9) | 38.3 (37.65–38.7) | 38.1 (37.5–38.8) | 38.1 (37.6–38.5) | 38.5 (38.0–39.0) | 38.75 (38.0–39.0) | 38.3 (37.85–39.0) |
| Cough | 1,724 (86.9) | 245 (84.5) | 63 (81.8) | 643 (87.5) | 246 (87.5) | 37 (84.1) | 71 (88.8) | 419 (88.0) |
| Sore throat | 1,067 (53.8) | 204 (70.3) | 50 (64.9) | 335 (45.6) | 185 (65.8) | 32 (72.7) | 46 (57.5) | 215 (45.2) |
| Rhinorrhea/Nasal obstruction | 1,092 (55.1) | 215 (74.1) | 41 (53.2) | 308 (41.9) | 179 (63.7) | 26 (59.1) | 60 (75.0) | 263 (55.3) |
| Influenza vaccination (2011–2012) | 430 (21.7) | 74 (25.5) | 23 (29.9) | 145 (19.7) | 71 (25.3) | 8 (18.2) | 24 (30.0) | 85 (17.9) |
DM, diabetes mellitus; BM, bone marrow; ILI, influenza-like illness.