• Antiviral resistance surveillance

Monitoring of antiviral resistance takes place through a number of surveillance initiatives and ad hoc studies. 

The World Health Organisation collates data through the Global Influenza Surveillance Network (GISN) and from WHO Collaborating Centres.  Data from European countries participating in the European Influenza Surveillance Scheme (EISS) under the aegis of the European Centre for Disease Prevention and Control (ECDC) have been provided by laboratories in the Community Network of Reference Laboratories for Human Influenza in Europe (CNRL) and the central testing laboratory at the Health Protection Agency, London, UK.

Ad hoc surveillance studies are undertaken by NISN and other groups.

Global data:
Oseltamivir resistance during 2008-09 northern hemisphere influenza season

During the period September 2008 – March 2009, laboratory data were reported to WHO from 36 countries.  Detailed data are available on the WHO website and are summarised below.  Following the emergence of pandemic influenza A (H1N1) in April 2009, surveillance of antiviral resistance has continued, co-ordinated by WHO.

Prevalence of antiviral drug resistance in currently circulating seasonal influenza viruses during the Northern Hemisphere season, 2008-2009

Map showing prevalence of oseltamivir resistant viruses (last quarter 2008 – first quarter 2009) (source: World Health Organisation)
Table: Seasonal influenza A (H1N1) resistant to oseltamivir  (last quarter 2008 – first quarter 2009) (source: World Health Organisation)

European data:
Monitoring influenza antiviral resistance in the EU, 2008-2009 season