Oseltamivir resistance during treatment of influenza A (H5N1) infection

N Engl J Med. 2005 Dec 22;353(25):2667-72. doi: 10.1056/NEJMoa054512.


Influenza A (H5N1) virus with an amino acid substitution in neuraminidase conferring high-level resistance to oseltamivir was isolated from two of eight Vietnamese patients during oseltamivir treatment. Both patients died of influenza A (H5N1) virus infection, despite early initiation of treatment in one patient. Surviving patients had rapid declines in the viral load to undetectable levels during treatment. These observations suggest that resistance can emerge during the currently recommended regimen of oseltamivir therapy and may be associated with clinical deterioration and that the strategy for the treatment of influenza A (H5N1) virus infection should include additional antiviral agents.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetamides / therapeutic use*
  • Adolescent
  • Adult
  • Amino Acid Substitution
  • Antiviral Agents / therapeutic use*
  • Base Sequence
  • Child
  • Drug Resistance, Viral*
  • Fatal Outcome
  • Female
  • Humans
  • Influenza A Virus, H5N1 Subtype* / genetics
  • Influenza A Virus, H5N1 Subtype* / isolation & purification
  • Influenza, Human / drug therapy*
  • Influenza, Human / virology
  • Lung / diagnostic imaging
  • Male
  • Neuraminidase / antagonists & inhibitors*
  • Neuraminidase / genetics
  • Oseltamivir
  • Pneumonia, Viral / diagnostic imaging
  • Pneumonia, Viral / virology
  • Radiography
  • Sequence Analysis, DNA
  • Viral Load


  • Acetamides
  • Antiviral Agents
  • Oseltamivir
  • Neuraminidase