ECDC monitors and reports on influenza transmission and virus circulation in Europe on a weekly basis throughout the flu season, in collaboration with WHO Regional Office for Europe, in the report Flu News Europe.
The case definition and case finding algorithm have been prepared for surveillance purposes only and they will be adjusted as the current avian influenza A(H7N9) situation develops.
Influenza pandemics occur when new influenza viruses appear that transmit efficiently between humans and to which a substantial proportion of the population is susceptible