Table 1.
Demographics, clinical diagnosis, and vaccination characteristics of the study population [n (%)].
| Variables | All Patients n (%) (n = 27,670) |
Test-Positive Cases n (%) (n = 11,128) |
Test-Negative Controls n (%) (n = 16,542) |
p-Value 1 |
|---|---|---|---|---|
| Influenza season | <0.001 | |||
| 2021–2022 | 6052 (21.9) | 2081 (18.7) | 3971 (24.0) | |
| 2022–2023 | 5078 (18.4) | 1669 (15.0) | 3409 (20.6) | |
| 2023–2024 | 16,540 (59.7) | 7378 (66.3) | 9162 (55.4) | |
| Age groups (years) | <0.001 | |||
| 0.5 ≤ age < 3 | 4628 (16.7) | 1313 (11.8) | 3315 (20) | |
| 3 ≤ age < 9 | 16,884 (61) | 6887 (61.9) | 9997 (60.4) | |
| 9 ≤ age < 18 | 6158 (22.3) | 2928 (26.3) | 3230 (19.6) | |
| Sex | 0.628 | |||
| Male | 15,349 (55.5) | 6193 (55.7) | 9156 (55.4) | |
| Female | 12,321 (44.5) | 4935 (44.3) | 7386 (44.6) | |
| Respiratory tract infection site | <0.001 | |||
| Upper | 18,712 (67.6) | 7984(71.7) | 10,728 (64.9) | |
| Lower | 8958 (32.4) | 3144(28.3) | 5814 (35.1) | |
| Month of sample collection | <0.001 | |||
| 1 | 5130 (18.5) | 2173 (19.5) | 2957 (17.1) | |
| 2 | 326 (1.2) | 56 (0.5) | 270 (1.7) | |
| 3 | 3004 (10.9) | 884 (7.9) | 2120 (12.9) | |
| 4 | 1958 (7.1) | 753 (6.8) | 1205 (7.4) | |
| 5 | 578 (2.1) | 188 (1.7) | 390 (2.5) | |
| 6 | 2039 (7.4) | 1259 (11.3) | 780 (4.8) | |
| 7 | 604 (2.2) | 206 (1.9) | 398 (2.5) | |
| 8 | 300 (1.1) | 25 (0.2) | 275 (1.8) | |
| 9 | 562 (2.0) | 85 (0.8) | 477 (2.8) | |
| 10 | 1254 (4.5) | 248 (2.2) | 1006 (6.1) | |
| 11 | 4711 (17.0) | 1792 (16.1) | 2919 (17.7) | |
| 12 | 7204 (26.0) | 3459 (31.1) | 3745 (22.7) | |
| Type of Influenza | ||||
| Influenza A | - | 7833 (70.4) | - | |
| Influenza B | - | 3976 (35.7) | - | |
| Vaccination status in the current season | <0.001 | |||
| Unvaccinated | 24,813 (89.7) | 10,280 (92.4) | 14,533 (87.8) | |
| Vaccinated | 2857 (10.3) | 848 (7.6) | 2009 (12.2) | |
| Vaccination status in the current and previous seasons | <0.001 | |||
| Unvaccinated | 17,788 (64.3) | 7511 (67.5) | 10,277 (62.1) | |
| Current season only | 1110 (4.0) | 332 (3.0) | 778 (4.7) | |
| Previous season only | 7025 (25.4) | 2769 (24.9) | 4256 (25.7) | |
| Current and previous season | 1747 (6.3) | 516 (4.6) | 1231 (7.5) | |
1 We used the chi-square test to assess the differences in demographic, clinical diagnosis, and vaccination characteristics between the positive case group and negative control group.