Drug resistance of influenza A (H1N1) pdm09 virus in Hebei, 2017–2020

  Objective  To analyze the resistance of influenza A (H1N1) pdm09 virus to neuraminidase inhibitors (NAIs) in Hebei province during 2017–2020 and provide evidence for the prevention and control of influenza．

  Methods  A total of 37 strains of influenza A (H1N1) pdm09 virus isolated in Hebei during 2017–2020 were selected for oseltamivir and zanamivi resistance tests with fluorescence radiation assay. A total of 38 strains of influenza A (H1N1) pdm09 virus were selected for neuraminidase (NA) sequencing analysis.

  Results  The median of half maximal inhibitory concentration (IC₅₀) of oseltamivir to strain A/Hebeixinhua/SWL1106/2017 was 30.98 nmol/L. To 36 virus strains, the average IC₅₀ of oseltamivir was of 0.46 nmol/L (ranged 0.07–1.14 nmol/L) while the average IC₅₀ of zanamivi was 0.27 nmol/L (ranged 0.07–0.85 nmol/L). Sequence analysis showed that 1 strain had H275Y mutation in amino acid of the NA gene, suggesting that the strain was oseltamivir resistant.

  Conclusion  The majority of influenza A (H1N1) pdm09 virus strains isolated in Hebei during 2017–2020 were sensitive to NAIs.