The Public Health Agency of Canada is recommending that health care providers in Canada not prescribe amantadine to treat and prevent influenza during the current flu season. This recommendation is based on test results from the 2005-2006 flu season and initial results from the 2006-2007 season.
The Public Health Agency has tested three influenza A isolates for amantadine resistance and found that one influenza A (H3N2) was resistant to amantadine. Given these findings and those of 2005-2006 season when approximately 80% influenza A isolates were resistant to amantadine, the Public Health Agency of Canada does not recommend the use of this drug for treatment or prevention of influenza for the 2006-2007 season. This recommendation will be revisited if new information becomes available.
At this time, oseltamivir (Tamiflu) or zanamivir (Relenza) should be selected if an antiviral medication is recommended for the treatment or prevention of influenza for the remainder of the 2006/2007 influenza season.
Testing of influenza isolates for the 2006-2007 season will continue and recommendations will be updated based on results.
The results are an important reminder that antiviral medications – which don’t provide immunity – should not replace annual influenza immunization for the prevention of influenza. Influenza immunization ? or the annual “flu shot” ? remains the most effective method of avoiding contracting influenza when combined with proper hygiene, including frequent hand washing and staying home when you are ill.
This year’s influenza vaccine includes a strain similar to the H3N2 virus in circulation and is expected to provide immunity to those who receive the flu shot this season.