The information intends to provide a profile on the proportion of strains with reduced antiviral susceptibility. The date refers to specimen reception by the laboratory. Numbers and trends presented here should be interpreted in light of the small specimen numbers in particular categories.
Antiviral susceptibility testing of influenza A(H1)pdm09 viruses in 2026
| Month | No. of virus isolates tested | Reduced susceptibility to oseltamivir* | Reduced susceptibility to baloxavir# | No. of positive samples tested | H275Y substitution | |||
|---|---|---|---|---|---|---|---|---|
| No. | % | No. | % | No. | % | |||
| Jan | 3 | 1 | 33% | 0 | 0% | 26 | 0 | 0% |
| Feb | 2 | 0 | 0% | 0 | 0% | 28 | 0 | 0% |
| Mar | 6 | 0 | 0% | 0 | 0% | 50 | 0 | 0% |
| Apr | 6 | 0 | 0% | 0 | 0% | 49 | 0 | 0% |
| May | 4 | 0 | 0% | 0 | 0% | 51 | 0 | 0% |
| Jun | 9 | 0 | 0% | 0 | 0% | 91 | 0 | 0% |
| Jul | 90 | 0 | 0% | |||||
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Antiviral susceptibility testing of influenza A(H3) viruses in 2026
| Month | No. of virus isolates tested | Reduced susceptibility to oseltamivir* | Reduced susceptibility to baloxavir# | ||
|---|---|---|---|---|---|
| No. | % | No. | % | ||
| Jan | 16 | 0 | 0% | 0 | 0% |
| Feb | 13 | 0 | 0% | 0 | 0% |
| Mar | 8 | 0 | 0% | 0 | 0% |
| Apr | 8 | 0 | 0% | 0 | 0% |
| May | 9 | 0 | 0% | 0 | 0% |
| Jun | 27 | 0 | 0% | 0 | 0% |
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Antiviral susceptibility testing of influenza B viruses in 2026
| Month | No. of virus isolates tested | Reduced susceptibility to oseltamivir* | Reduced susceptibility to baloxavir# | ||
|---|---|---|---|---|---|
| No. | % | No. | % | ||
| Jan | 2 | 0 | 0% | 0 | 0% |
| Feb | 6 | 0 | 0% | 0 | 0% |
| Mar | 7 | 0 | 0% | 0 | 0% |
| Apr | 6 | 0 | 0% | 0 | 0% |
| May | 7 | 0 | 0% | 0 | 0% |
| Jun | 4 | 0 | 0% | 0 | 0% |
| Jul | |||||
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* Since May 2026, a sequencing-first approach is adopted and phenotypic assay is used to confirm cases with neuraminidase (NA) amino acid substitutions associated with reduced susceptibility to antivirals.
# By genotypic characterization.