Influenza negative | Influenza positive | A (H1N1)pdm09 | A (H3N2) | A not subtyped | B/Yamagata | B/Victoria | B not subtyped | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
N = 7245 | N = 2895 | N = 76 | N = 1840 | N = 129 | N = 108 | N = 618 | N = 135 | ||||||||||||||||
Characteristic | n | % | n | % | P vs. negative | n | % | P vs. negative | n | % | P vs. negative | n | % | P vs. negative | n | % | P vs. negative | n | % | P vs. negative | n | % | P vs. negative |
Age in years, median (range) | 12 (0–105) | 28 (0–103) | < 0.001 | 35 (0–84) | 0.083 | 35 (0–103) | < 0.001 | 48 (0–102) | < 0.001 | 13 (0–92) | 0.840 | 18 (0–89) | 0.008 | 7 (0–94) | 0.139 | ||||||||
Age group | < 0.0001 | 0.0001 | < 0.0001 | < 0.0001 | 0.0003 | < 0.0001 | < 0.0001 | ||||||||||||||||
0–1 y | 2361 | 32.8 | 331 | 11.9 | 11 | 14.5 | 220 | 12.5 | 16 | 16.0 | 20 | 19.8 | 47 | 7.6 | 20 | 14.9 | |||||||
2–4 y | 906 | 12.6 | 311 | 11.2 | 12 | 15.8 | 162 | 9.2 | 13 | 13.0 | 16 | 15.8 | 86 | 13.9 | 24 | 17.9 | |||||||
5–17 y | 446 | 6.2 | 381 | 13.7 | 7 | 9.2 | 143 | 8.1 | 7 | 7.0 | 15 | 14.9 | 176 | 28.5 | 35 | 26.1 | |||||||
18–49 y | 1305 | 18.1 | 795 | 28.7 | 23 | 30.3 | 440 | 25.1 | 15 | 15.0 | 10 | 9.9 | 282 | 45.6 | 26 | 19.4 | |||||||
50–64 y | 540 | 7.5 | 195 | 7.0 | 13 | 17.1 | 159 | 9.1 | 3 | 3.0 | 12 | 11.9 | 5 | 0.8 | 4 | 3.0 | |||||||
65–74 y | 565 | 7.9 | 228 | 8.2 | 7 | 9.2 | 178 | 10.1 | 15 | 15.0 | 7 | 6.9 | 11 | 1.8 | 10 | 7.5 | |||||||
75–84 y | 631 | 8.8 | 272 | 9.8 | 3 | 3.9 | 223 | 12.7 | 16 | 16.0 | 11 | 10.9 | 9 | 1.5 | 12 | 9.0 | |||||||
≥ 85 y | 441 | 6.1 | 260 | 9.4 | 0 | 0.0 | 230 | 13.1 | 15 | 15.0 | 10 | 9.9 | 2 | 0.3 | 3 | 2.2 | |||||||
Sex | < 0.0001 | 0.1374 | < 0.0001 | 0.3877 | 0.6826 | < 0.0001 | 0.5137 | ||||||||||||||||
Male | 3766 | 52.0 | 1339 | 46.3 | 33 | 43.4 | 859 | 46.7 | 72 | 55.8 | 54 | 50.0 | 254 | 41.1 | 74 | 54.8 | |||||||
Female | 3479 | 48.0 | 1556 | 53.7 | 43 | 56.6 | 981 | 53.3 | 57 | 44.2 | 54 | 50.0 | 364 | 58.9 | 61 | 45.2 | |||||||
Chronic conditions | < 0.0001 | 0.1801 | < 0.0001 | < 0.0001 | 0.0025 | < 0.0001 | 0.6485 | ||||||||||||||||
0 | 4765 | 65.8 | 1661 | 57.4 | 44 | 57.9 | 894 | 48.6 | 51 | 39.5 | 58 | 53.7 | 528 | 85.4 | 92 | 68.1 | |||||||
1 | 1240 | 17.1 | 572 | 19.8 | 19 | 25.0 | 415 | 22.6 | 27 | 20.9 | 18 | 16.7 | 71 | 11.5 | 24 | 17.8 | |||||||
≥2 | 1240 | 17.1 | 662 | 22.9 | 13 | 17.1 | 531 | 28.9 | 51 | 39.5 | 32 | 29.6 | 19 | 3.1 | 19 | 14.1 | |||||||
Previously hospitalised (last 12 months) | 0.0163 | 0.2604 | 0.9969 | 0.6372 | 0.8445 | 0.0002 | 0.0086 | ||||||||||||||||
No | 5029 | 73.6 | 1659 | 76.2 | 58 | 79.5 | 924 | 73.6 | 44 | 71.0 | 53 | 72.6 | 494 | 80.5 | 94 | 84.7 | |||||||
Yes | 1802 | 26.4 | 518 | 23.8 | 15 | 20.5 | 331 | 26.4 | 18 | 29.0 | 20 | 27.4 | 120 | 19.5 | 17 | 15.3 | |||||||
Underlying chronic conditions | |||||||||||||||||||||||
Cardiovascular disease | 1298 | 17.9 | 796 | 27.5 | < 0.0001 | 17 | 22.4 | 0.3145 | 627 | 34.1 | < 0.0001 | 60 | 46.5 | < 0.0001 | 37 | 34.3 | < 0.0001 | 30 | 4.9 | < 0.0001 | 28 | 20.7 | 0.3970 |
Chronic obstructive pulmonary disease | 802 | 11.1 | 206 | 7.1 | < 0.0001 | 8 | 10.5 | 0.8806 | 159 | 8.6 | 0.0025 | 10 | 7.8 | 0.2328 | 10 | 9.3 | 0.5513 | 16 | 2.6 | < 0.0001 | 7 | 5.2 | 0.0301 |
Asthma | 276 | 3.8 | 187 | 6.5 | < 0.0001 | 6 | 7.9 | 0.0656 | 147 | 8.0 | < 0.0001 | 14 | 10.9 | < 0.0001 | 8 | 7.4 | 0.0541 | 8 | 1.3 | 0.0013 | 4 | 3.0 | 0.6100 |
Immunodeficiency/organ transplant | 155 | 2.1 | 67 | 2.3 | 0.5867 | 3 | 3.9 | 0.2806 | 49 | 2.7 | 0.1758 | 7 | 5.4 | 0.0116 | 3 | 2.8 | 0.6497 | 2 | 0.3 | 0.0020 | 3 | 2.2 | 0.9475 |
Diabetes | 687 | 9.5 | 362 | 12.5 | < 0.0001 | 11 | 14.5 | 0.1405 | 292 | 15.9 | < 0.0001 | 33 | 25.6 | < 0.0001 | 13 | 12.0 | 0.3693 | 5 | 0.8 | < 0.0001 | 8 | 5.9 | 0.1610 |
Renal impairment | 409 | 5.6 | 208 | 7.2 | 0.0034 | 4 | 5.3 | 0.8858 | 161 | 8.8 | < 0.0001 | 11 | 8.5 | 0.1616 | 7 | 6.5 | 0.7089 | 19 | 3.1 | 0.0069 | 7 | 5.2 | 0.8184 |
Neuromuscular disease | 234 | 3.2 | 192 | 6.6 | < 0.0001 | 2 | 2.6 | 0.7690 | 147 | 8.0 | < 0.0001 | 15 | 11.6 | < 0.0001 | 8 | 7.4 | 0.0157 | 12 | 1.9 | 0.0775 | 9 | 6.7 | 0.0266 |
Neoplasm | 311 | 4.3 | 168 | 5.8 | 0.0012 | 0 | 0.0 | 0.0649 | 133 | 7.2 | < 0.0001 | 20 | 15.5 | < 0.0001 | 7 | 6.5 | 0.2670 | 4 | 0.6 | < 0.0001 | 5 | 3.7 | 0.7377 |
Cirrhosis/liver disease | 97 | 1.3 | 38 | 1.3 | 0.9171 | 0 | 0.0 | 0.3099 | 29 | 1.6 | 0.4372 | 3 | 2.3 | 0.3369 | 1 | 0.9 | 0.7103 | 4 | 0.6 | 0.1428 | 1 | 0.7 | 0.5475 |
Autoimmune disease | 96 | 1.3 | 35 | 1.2 | 0.6402 | 1 | 1.3 | 0.9944 | 16 | 0.9 | 0.1139 | 1 | 0.8 | 0.5869 | 4 | 3.7 | 0.0341 | 12 | 1.9 | 0.2061 | 1 | 0.7 | 0.5548 |
Pregnant (women 15–45 y) | 459 | 58.0 | 481 | 82.7 | < 0.0001 | 1 | 10.0 | 0.0023 | 272 | 83.7 | < 0.0001 | 2 | 28.6 | 0.1164 | 1 | 14.3 | 0.0198 | 196 | 89.9 | < 0.0001 | 9 | 56.3 | 0.8866 |
Obese (all ages) | 1083 | 15.6 | 374 | 14.6 | 0.1967 | 18 | 25.4 | 0.0250 | 271 | 17.0 | 0.1905 | 13 | 17.1 | 0.7231 | 17 | 18.3 | 0.4834 | 46 | 7.4 | < 0.0001 | 12 | 9.6 | 0.0654 |
Outpatient consultations last 3 months | 0.6362 | 0.7448 | 0.0005 | 0.7360 | 0.0061 | 0.0120 | 0.0008 | ||||||||||||||||
0 | 2504 | 36.7 | 779 | 35.8 | 25 | 34.2 | 388 | 30.9 | 20 | 32.3 | 40 | 54.8 | 262 | 42.7 | 48 | 43.2 | |||||||
1 | 1448 | 21.2 | 480 | 22.0 | 14 | 19.2 | 287 | 22.9 | 15 | 24.2 | 11 | 15.1 | 121 | 19.7 | 35 | 31.5 | |||||||
≥ 2 | 2879 | 42.1 | 918 | 42.2 | 34 | 46.6 | 580 | 46.2 | 27 | 43.5 | 22 | 30.1 | 231 | 37.6 | 28 | 25.2 | |||||||
Smoking habits (patients ≥18 y) | < 0.0001 | 0.0753 | < 0.0001 | 0.1387 | 0.9041 | 0.1663 | 0.0818 | ||||||||||||||||
Never smoker | 4106 | 57.0 | 1598 | 57.5 | 42 | 56.0 | 993 | 56.7 | 62 | 53.9 | 57 | 56.4 | 367 | 59.5 | 84 | 64.1 | |||||||
Past smoker | 1366 | 19.0 | 640 | 23.0 | 21 | 28.0 | 459 | 26.2 | 23 | 20.0 | 18 | 17.8 | 98 | 15.9 | 15 | 11.5 | |||||||
Current smoker | 1728 | 24.0 | 542 | 19.5 | 12 | 16.0 | 300 | 17.1 | 30 | 26.1 | 26 | 25.7 | 152 | 24.6 | 32 | 24.4 | |||||||
Functional status impairment (Barthel score; patients ≥65 y) | 0.0764 | 0.5686 | 0.1750 | 0.9911 | 0.4228 | 0.6788 | 0.0012 | ||||||||||||||||
Total (0–15) | 106 | 6.8 | 24 | 3.9 | 0 | 0.0 | 21 | 4.2 | 3 | 7.3 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |||||||
Severe (20–35) | 35 | 2.3 | 15 | 2.4 | 0 | 0.0 | 11 | 2.2 | 1 | 2.4 | 0 | 0.0 | 0 | 0.0 | 3 | 13.0 | |||||||
Moderate (40–55) | 62 | 4.0 | 31 | 5.0 | 0 | 0.0 | 26 | 5.2 | 1 | 2.4 | 0 | 0.0 | 1 | 4.5 | 3 | 13.0 | |||||||
Mild (60–90) | 364 | 23.5 | 136 | 22.1 | 4 | 44.4 | 109 | 21.9 | 10 | 24.4 | 6 | 24.0 | 5 | 22.7 | 3 | 13.0 | |||||||
Minimal (95–100) | 985 | 63.5 | 409 | 66.5 | 5 | 55.6 | 330 | 66.4 | 26 | 63.4 | 19 | 76.0 | 16 | 72.7 | 14 | 60.9 | |||||||
Sampling time | < 0.0001 | 0.0051 | < 0.0001 | 0.0797 | 0.7704 | < 0.0001 | 0.3919 | ||||||||||||||||
0–2 days | 2374 | 33.1 | 1211 | 42.0 | 16 | 21.1 | 830 | 45.3 | 54 | 41.9 | 35 | 32.7 | 237 | 38.3 | 40 | 29.6 | |||||||
3–4 days | 2521 | 35.2 | 1052 | 36.5 | 22 | 28.9 | 657 | 35.9 | 38 | 29.5 | 41 | 38.3 | 244 | 39.5 | 53 | 39.3 | |||||||
5–7 days | 1941 | 27.1 | 564 | 19.5 | 34 | 44.7 | 303 | 16.5 | 35 | 27.1 | 28 | 26.2 | 132 | 21.4 | 39 | 28.9 | |||||||
8–9 days | 335 | 4.7 | 59 | 2.0 | 4 | 5.3 | 42 | 2.3 | 2 | 1.6 | 3 | 2.8 | 5 | 0.8 | 3 | 2.2 | |||||||
Influenza vaccination ≥15 days from symptom onset | 938 | 13.0 | 279 | 9.6 | < 0.0001 | 7 | 9.2 | 0.3339 | 221 | 12.0 | 0.2825 | 10 | 7.8 | 0.0806 | 9 | 8.3 | 0.1554 | 25 | 4.1 | < 0.0001 | 8 | 5.9 | 0.0156 |
Influenza vaccination ≥15 days from symptom onset (age ≥ 65) | 673 | 39.9 | 195 | 22.1 | < 0.0001 | 1 | 10.0 | 0.0541 | 175 | 24.4 | < 0.0001 | 8 | 10.7 | < 0.0001 | 6 | 17.1 | 0.0064 | 1 | 4.6 | 0.0008 | 4 | 15.4 | 0.0112 |
Influenza vaccination ≥15 days from symptom onset (targeted groups) | 869 | 18.4 | 256 | 11.1 | < 0.0001 | 7 | 13.0 | 0.3047 | 214 | 13.6 | < 0.0001 | 8 | 7.2 | 0.0025 | 7 | 11.1 | 0.1373 | 14 | 3.1 | < 0.0001 | 7 | 9.7 | 0.0586 |