Increased adamantane resistance in influenza A(H3) viruses in Australia and neighbouring countries in 2005.

The prevention and control of disease caused by seasonal and potential pandemic influenza viruses is currently managed by the use influenza vaccines and antivirals. The adamantanes (amantadine and rimantadine) were the first antivirals licensed for use against influenza A viruses and have been used extensively in some countries. Since the early 2000s increased resistance to these drugs has been reported especially in the A(H3) viruses. In this study we analysed recent human influenza A strains isolated in Australia and regionally for evidence of resistance to adamantanes and found evidence of significant resistant emerging during 2005.