Have other types of influenza viruses tested resistant to oseltamivir?
The elevated resistance to oseltamivir appears currently limited to seasonal H1N1 viruses and does not involve circulating H3N2 or influenza B viruses. All of the resistant H1N1 viruses in Europe have a specific resistance mutation in the viral neuraminidase (i.e., a histidine to tyrosine substitution at amino acid 274). Influenza H1N1 has been the predominant influenza A virus circulating (with a smaller contribution of influenza B viruses) in many countries in Europe and other parts of the northern hemisphere this season, but influenza A H3N2 or a mixture of A and B viruses have circulated in other countries. Furthermore, patterns may change as the season progresses Updates are available at Seasonal influenza activity in the world, 2008.
