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


Preliminary results from the National Virus Reference Laboratory (NVRL) on antiviral drug susceptibility among seasonal influenza viruses circulating in Ireland has revealed that some of the A (H1N1) viruses in circulation this winter are resistant to the antiviral drug, oseltamivir (also know by the brand name Tamiflu). The NVRL conducted nucleotide sequencing on specimens taken by sentinel GPs between December 2007 and January 2008. As of February 20th 2008, three of 29 specimens (10.3%) tested by the NVRL have shown resistance to oseltamivir. The NVRL is currently arranging for further Irish samples to be tested. To date, oseltamivir resistant viruses have been detected in 15 European countries (including Ireland), the USA, Canada, Australia and Hong Kong. In Europe, the highest proportion of resistant viruses to date has been in Norway where 63 (66%) of the 95 samples tested positive for resistance to oseltamivir. The second highest proportion was noted in France with 80 (39%) of 207 specimens showing oseltamivir resistance. The latest European data is available from the European Centre for Disease Prevention and Control (ECDC).

Experts from ECDC, the European Commission, the European Influenza Surveillance Scheme (EISS) and the World Health Organization (WHO) are currently assessing the significance of this information. An interim risk assessment has been published by ECDC.

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. 

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