What can countries expect during the 2016–2017 influenza season?
Early influenza activity in the European Region mainly affecting the elderly
This winter, influenza activity in the Region increased earlier than in recent years. Influenza A(H3N2) virus represents about 98% of influenza A viruses detected and typed. Health providers should therefore preferentially suspect and treat severe influenza in the elderly, and should consider the use of influenza-specific antiviral medicines even in patients who have been vaccinated. The distribution of viruses may change over the course of a winter, and so it is currently unclear whether or not the predominant virus will remain the same.
Pooled analysis of data from 19 European Union/European Economic Area countries or regions reporting to the European Monitoring of Excess Mortality for Public Health project indicates that excess all-cause mortality seems to have been increasing among the elderly in recent weeks, notably in France and Portugal. This may be due to influenza and, for some countries, the extremely cold weather in recent weeks. However, the observed increase in excess mortality is prone to uncertainty due to delayed adjustment and should be interpreted with caution.
So far this winter, circulating A(H3N2) viruses are antigenically similar to the vaccine strain. Early monitoring of vaccine effectiveness in Scandinavia suggests levels of effectiveness within estimates from multi-country studies during recent years.
Flu News Europe
Countries conduct surveillance to characterize the circulating influenza viruses, to determine the timing of the influenza season and the potential severity of disease, and to provide data to WHO for regional and global updates. WHO/Europe and the European Centre for Disease Prevention and Control collaborate to collect and analyse influenza surveillance data from WHO European Member States and present these data each 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 helps prepare countries for the peak of the season, when health services may become overburdened by the number of patients.
As the influenza season progresses in 2017, Flu News Europe will continue to report on the situation.
Who is at risk from seasonal influenza in Europe
During the winter months, influenza may infect up to 20% of the population, depending on which viruses are circulating. People at increased risk for severe disease once infected include the elderly, pregnant women, young children, immune-compromised people and people with chronic underlying medical conditions. These groups represent a significant proportion of the population in the WHO European Region.
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 age groups.
WHO recommends that everyone at risk of severe disease as a result of infection with influenza, as well as health care workers, be offered seasonal influenza vaccination. As it is not possible to predict if one influenza virus will predominate in a particular season, seasonal influenza vaccines should cover all viruses that are anticipated to circulate, namely influenza A(H3N2), influenza A(H1N1) and influenza B.