Table 1.
Selection of patients and results of RT-PCR
| St. Petersburg | Moscow | Czech Republic | Turkey | Beijing | Valencia | Total | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Category | n | % | n | % | n | % | n | % | n | % | n | % | n | % |
| Screened admissions | 3164 | 1934 | 123 | 1409 | 1425 | 12,496 | 20,551 | |||||||
| Exclusion criteria | ||||||||||||||
| Non resident | 21 | 0.7 | 95 | 4.9 | 12 | 9.8 | 73 | 5.2 | 5 | 0.4 | 50 | 0.4 | 256 | 1.2 |
| Institutionalised | 14 | 0.4 | 14 | 0.7 | 2 | 1.6 | 17 | 1.2 | 2 | 0.1 | 800 | 6.4 | 849 | 4.1 |
| Previous discharge <30 days | 31 | 1.0 | 51 | 2.6 | 8 | 6.5 | 216 | 15.3 | 13 | 0.9 | 2283 | 18.3 | 2602 | 12.7 |
| Unable to communicate | 20 | 0.6 | 47 | 2.4 | 2 | 1.6 | 125 | 8.9 | 0 | 0.0 | 782 | 6.3 | 976 | 4.7 |
| Not giving consent | 100 | 3.2 | 32 | 1.7 | 14 | 11.4 | 47 | 3.3 | 15 | 1.1 | 504 | 4.0 | 712 | 3.5 |
| No ILI symptoms ≥5 years of age | 19 | 0.6 | 25 | 1.3 | 1 | 0.8 | 131 | 9.3 | 18 | 1.3 | 2903 | 23.2 | 3097 | 15.1 |
| Admission within 7 days of symptoms onset | 181 | 5.7 | 150 | 7.8 | 4 | 3.3 | 110 | 7.8 | 44 | 3.1 | 745 | 6.0 | 1234 | 6.0 |
| Previous influenza infection | 1 | 0.0 | 0 | 0.0 | 0 | 0.0 | 7 | 0.5 | 0 | 0.0 | 1 | 0.0 | 9 | 0.0 |
| Onset of symptoms to swab >9 days | 0 | 0.0 | 1 | 0.1 | 0 | 0.0 | 2 | 0.1 | 0 | 0.0 | 1 | 0.0 | 4 | 0.0 |
| Sample inadequate | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 5 | 0.0 | 5 | 0.0 |
| Sample lost | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 0.1 | 1 | 0.0 | 2 | 0.0 |
| Recruited outside periods with continuous influenza positive admissions | 31 | 1.0 | 115 | 5.9 | 1 | 0.8 | 65 | 4.6 | 178 | 12.5 | 764 | 6.1 | 1154 | 5.6 |
| Included with valid laboratory results | 2715 | 85.8 | 1400 | 72.4 | 79 | 64.2 | 614 | 43.6 | 1149 | 80.6 | 3657 | 29.3 | 9614 | 46.8 |
| RT-PCR result | ||||||||||||||
| Influenza negative | 2113 | 77.8 | 966 | 69.0 | 20 | 25.3 | 543 | 88.4 | 875 | 76.2 | 2920 | 79.8 | 7437 | 77.4 |
| Influenza positive | 602 | 22.2 | 434 | 31.0 | 59 | 74.7 | 71 | 11.6 | 274 | 23.8 | 737 | 20.2 | 2177 | 22.6 |
| Subtype and lineagea | ||||||||||||||
| A(H1N1)pdm09 | 47 | 7.8 | 30 | 6.9 | 7 | 11.9 | 26 | 36.6 | 1 | 0.4 | 10 | 1.4 | 121 | 5.6 |
| A(H3N2) | 267 | 44.3 | 163 | 37.6 | 33 | 55.9 | 6 | 8.5 | 163 | 59.5 | 611 | 82.9 | 1243 | 57.1 |
| A not subtyped | 48 | 8.0 | 9 | 2.1 | 2 | 3.3 | 0 | 0.0 | 0 | 0.0 | 47 | 6.4 | 106 | 4.9 |
| B/Yamagata lineage | 258 | 42.9 | 175 | 40.3 | 16 | 27.1 | 0 | 0.0 | 109 | 39.8 | 65 | 8.8 | 623 | 28.6 |
| B/Victoria lineage | 0 | 0 | 10 | 2.3 | 0 | 0 | 0 | 0.0 | 1 | 0.4 | 0 | 0.0 | 11 | 0.5 |
| B not subtypedb | 0 | 0 | 52 | 12.0 | 2 | 3.4 | 39 | 54.9 | 0 | 0.0 | 4 | 0.5 | 97 | 4.5 |
Abbreviations: ILI, influenza-like disease; RT-PCR, reverse transcriptase-polymerase chain reaction
aBecause there were 24 mixed infections, each involving two different influenza viruses, the sum by strain may be greater than the number of patients included with lab results. Percentages are reported by total of influenza-positive cases
bFor Turkey and Valencia, all B not subtyped were assumed to be B/Yamagata lineage based on virus circulation at these sites. This assumption was not applied for Moscow because of a mixed pattern of influenza B circulation