Surveillance

Continuous global surveillance of influenza is key. The World Health Organization (WHO) has a network of 112 National Influenza Centres that monitor influenza activity and isolate avian influenza viruses across all continents. National Influenza Centres report the emergence of an unusual influenza virus immediately to the WHO Global Influenza Programme or to one of the four WHO Collaborating Centres. Rapid detection of unusual influenza outbreaks, isolation of possible pandemic viruses and immediate alerts to the WHO system by national authorities is vital for mounting a timely and efficient response to pandemics.