What can countries expect during this year’s influenza season?
During the influenza season, influenza may infect up to 20% of the population, depending on which viruses are circulating. Infected people at increased risk for severe disease include pregnant women, the very young and the very old, immune-compromised people and people with chronic underlying medical conditions. These groups represent a significant proportion of the population in the WHO European Region. According to a paper entitled "Annual public health and economic benefits of seasonal influenza vaccination: a European estimate" published by BMC Public Health in 2014, these groups account for 36% of the population in the EU alone (approximately 180 million people).
Influenza A(H3N2) virus is known to cause severe disease and death in the elderly, while influenza A(H1N1) virus, which caused the 2009 pandemic and which now circulates as seasonal influenza, is more likely to cause severe disease in younger, otherwise healthy adults.
WHO recommends that everyone at risk for severe influenza and health care workers be offered seasonal influenza vaccine. As it is not possible to predict which influenza virus will predominate in a particular season, seasonal influenza vaccines include influenza A(H3N2) and A(H1N1) and influenza B. Countries conduct surveillance to characterize the circulating influenza viruses, to determine the timing of the season and the potential severity of disease and to provide data to WHO for regional and global updates.
Flu News Europe
WHO/Europe and the European Centre for Disease Prevention and Control (ECDC) collaborate to analyse influenza surveillance data from all 53 WHO European Member states and present it every week in the Flu News Europe bulletin. Knowing how influenza is spreading through the Region (often in a west–east pattern) and which virus predominates prepares countries for the peak of the season, when health services may become overburdened by the numbers of patients.
The 2014–2015 influenza season was "severe"
The 2014–2015 influenza season was considered particularly severe, with 'flu suspected to have contributed to an abnormally large number of deaths among older people', according to a report from the European project for monitoring excess mortality for public health action (EuroMOMO). During the 2015 winter season, an estimated 217 000 premature deaths were registered among older people in the EU alone, many of which were probably due to influenza, although other factors might also have contributed, including cold snaps.
Influenza activity this season
So far this season, influenza activity has been detected mainly in northern and southern countries; influenza A(H1N1) virus represents about 80% of influenza A viruses. Health providers should therefore suspect and treat severe influenza in younger, otherwise healthy adults.
As the flu season progresses in 2016, Flu News Europe will continue to report on the situation.