Resistance to oseltamivir (Tamiflu) found in some European influenza virus samples


Preliminary results from a survey of antiviral drug susceptibility among seasonal influenza viruses circulating in Europe has revealed that some of the A(H1N1) viruses in circulation this winter are resistant to the antiviral drug, oseltamivir (also known by the brand name Tamiflu). So far, 437 influenza A(H1N1) viruses isolated during November 2007 to January 2008 from eighteen European countries have been tested. Of these 59 (13.5%) have shown evidence of resistance to oseltamivir. The highest level of resistance has been seen in Norway, where 26 of 37 samples (70%) have been resistant. In the UK, 8 of 162 samples (4.9%) have been resistant. The National Virus Reference Laboratory is currently arranging for Irish samples to be tested. This information is published in Eurosurveillance.

Experts from the European Centre for Disease Prevention and Control (ECDC), the European Commission, and WHO are currently assessing the significance of this information. An interim risk assessment, prepared by ECDC, and based on the limited data currently available, is available here. Frequently Asked Questions, prepared by WHO/ECDC are available here.

The current influenza vaccine provides good protection against A/H1N1 viruses. Current national guidance on use of antivirals for treatment and prophylaxis of influenza remain in place though they are being kept under review. For information on seasonal influenza and how to protect yourself against it click here