Influenza virus resistance to oseltamivir: what are the implications?

Surveillance Findings - Influenza caused by an oseltamivir-resistant influenza A(H1N1) virus was widespread across Europe during the 2007–08 winter. - About 25% of A(H1N1) viruses tested in the European Influenza Surveillance Scheme (EISS) were resistant with an H274Y mutation in the neuraminidase glycoprotein. - Early indications during the 2008–09 season are that a large proportion of circulating A(H1N1) viruses have retained oseltamivir resistance, and that the resistant virus will likely become dominant in the United States but not in Europe. - Further analyses have indicated that these oseltamivir-resistant A(H1N1) viruses retain sensitivity to zanamivir and the M2 ion channel inhibitors (M2Is). (aut. ref.