Table 2. Influenza subtypes and lineages with and without reduced inhibition following antiviral susceptibility testing to oseltamivir reported to TESSy, EU/EEA, weeks 40/2023 through 9/2024 (n = 2,176).
| Level of susceptibility | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | ||
| Oseltamivir susceptibility | NI | AANI | AAHRI | AARI | Total | ||||
| Influenza A | |||||||||
| A(H1)pdm09 | 185 | 13.0 | 1,239 | 86.8 | 2 | 0.1a | 1b | 0.1 | 1,427 |
| A(H3) | 54 | 10.5 | 458 | 89.5 | 0 | 0 | 512 | ||
| Influenza B | |||||||||
| B/Victoria lineage | 21 | 32.8 | 43 | 67.2 | 0 | 0 | 64 | ||
| Total | 260 | 13.0 | 1,740 | 86.9 | 2 | 0.1 | 1 | 0 | 2,003 |
| Zanamivir susceptibility | NI | AANI | AAHRI | AARI | Total | ||||
| Influenza A | |||||||||
| A(H1)pdm09 | 185 | 13.0 | 1,242 | 87.0 | 0 | 0 | 1,427 | ||
| A(H3) | 54 | 10.5 | 458 | 89.5 | 0 | 0 | 512 | ||
| Influenza B | |||||||||
| B/Victoria lineage | 21 | 32.8 | 43 | 67.2 | 0 | 0 | 64 | ||
| Total | 260 | 13.0 | 1,743 | 87.0 | 0 | 0 | 2,003 | ||
| Baloxavir marboxil susceptibility | AANS | AARS | Total | ||||||
| Influenza A | |||||||||
| A(H1)pdm09 | 1,113 | 100.0 | 0 | 1,113 | |||||
| A(H3) | 400 | 99.5 | 2 | 0.5c | 402 | ||||
| Influenza B | |||||||||
| B/Victoria lineage | 38 | 100.0 | 0 | 38 | |||||
| Total | 1,551 | 100.0 | 2 | 0.1 | 1,553 | ||||
AA: amino acid (refers to genotypic testing result); EEA: European Economic Area; EU: European Union; NI: normal inhibition; NS: normal susceptibility; HRI: highly reduced inhibition; RI: reduced inhibition; RS: reduced susceptibility; TESSy: The European Surveillance System.
a These viruses carried the mutation NA:H275Y.
b This virus carried the mutation NA:I223T.
c These viruses carried the mutation PA:L28P.