Sensitivity of H5N1 Influenza Viruses to Oseltamivir: An Update

Continued worldwide circulation of highly pathogenic influenza A (H5N1) viruses has raised concerns that they might adapt to humans and cause a pandemic. Preparedness plans rely on influenza vaccines and on the prophylactic and therapeutic use of neuraminidase inhibitors, especially the orally available drug oseltamivir. Although the efficacy of oseltamivir is well established for uncomplicated seasonal influenza, questions remain about its clinical effectiveness for human H5N1 infections. In this review, available data on the sensitivity of H5N1 viruses to oseltamivir in vitro, in animal models and in human patients are discussed. The factors that might limit the efficacy of oseltamivir treatment for human H5N1 infections are also discussed, in addition to options for improving treatment efficacy and limiting the development of drug resistance.