Table 3. Influenza viruses characterised by clade, amino acid substitutions and study site, five European studies, interim influenza season 2019/20 (n = 605).
| Influenza virus | Clade | DK-H/DK-PCa | ES-PCb | EU-PCc,d | UK-PCd | ||||
|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | ||
| Total influenza A(H1N1)pdm09 | n = 505 | n = 566 | n = 496 | n = 50 | |||||
| Sequenced | 72 | 15 | 86 | 15 | 46 | 9 | 8 | 16 | |
| A/Norway/3433/2018-like | 6B.1A5A | 56 | 78 | 84 | 98 | 43 | NC | 7 | NC |
| A/Switzerland/3330/2017-like | 6B.1A5B | 15 | 21 | 2 | 2 | 3 | NC | 0 | NC |
| A/Slovenia/1489/2019-like | 6B.1A7 | 1 | 1 | 0 | 0 | 0 | NC | 0 | NC |
| A/Brisbane/02/2018-like | 6B.1A1 | 0 | 0 | 0 | 0 | 0 | NC | 0 | NC |
| A/Ireland/84630/2018-like | 6B.1A6 | 0 | 0 | 0 | 0 | 0 | NC | 1 | NC |
| Total influenza A(H3N2) | n = 572 | n = 75 | n = 250 | n = 675 | |||||
| Sequenced | 68 | 12 | 23 | 31 | 75 | 30 | 168 | 25 | |
| A/South Australia/34/2019-like | 3C.2a1b + T131K | 27 | 40 | 6 | NC | 21 | 28 | 13 | 8 |
| A/La Rioja/2202/2018-like | 3C.2a1b + T135K-A | 1 | 1 | 9 | NC | 10 | 13 | 1 | 1 |
| A/Hong Kong/2675/2019-like | 3C.2a1b + T135K-B | 9 | 13 | 1 | NC | 1 | 1 | 4 | 2 |
| A/Kansas/14/2017-like | 3C.3a | 31 | 46 | 7 | NC | 43 | 57 | 150 | 89 |
| Total influenza B | n = 213 | n = 285 | n = 317 | n = 8 | |||||
| Sequencede | 8 | 4 | 0 | 0 | 46 | 15 | 5 | 63 | |
| Total B/Victoria among sequenced | 8 | NC | 0 | NC | 46 | NC | 5 | NC | |
| B/Colorado/06/2017-like | 1A (del162–163) | 0 | NC | 0 | NC | 1 | NC | 0 | NC |
| B/Hong Kong/269/201-like | 1A (del162–164)A | 0 | NC | 0 | NC | 0 | NC | 0 | NC |
| B/Washington/02/2019-like | 1A (del162–164)B | 8 | NC | 0 | NC | 45 | NC | 5 | NC |
DK-PC: Denmark primary care study; DK-H: Denmark hospital study; ES-PC: Spain primary care study; EU-PC: European Union primary care multicentre I-MOVE study; I-MOVE: Influenza – Monitoring Vaccine Effectiveness in Europe; NC: not calculated (percentages not shown where denominators < 60); UK-PC: United Kingdom primary care study.
a DK-H and DK-PC samples are combined; sequence information is based on influenza-positive samples received for surveillance at the National Influenza Center Denmark from week 40/2019 and 4/2020.
b Specimens sequenced from Spain originate from the entire National Influenza Surveillance System in weeks 40/2019 to 4/2020.
c Two specimens from ES-PC also included in EU-PC data.
d At time of publishing not all specimens from the study period were processed.
e No B/Yamagata samples had been sequenced at the time of publishing.