Weekly influenza update, week 19, May 2018
In collaboration with WHO Regional Office for Europe, ECDC monitors and reports on influenza activity in Europe on a weekly basis throughout the flu season.
- Influenza activity had returned to inter-season levels in most of the countries in the Region.
- 10% of the individuals sampled from primary healthcare settings tested positive for influenza viruses (compared to 6% in the previous week).
2017/18 season overview
- Influenza viruses circulated at high levels in the Region between weeks 52/2017 and 12/2018 (based on increased proportions - 40% and above - of sentinel specimens testing positive for influenza viruses). This is longer than in recent seasons and may have contributed to the severity of this season.
- The majority of influenza viruses detected were type B, representing a high level of circulation of influenza B viruses compared to recent seasons. B/Yamagata lineage viruses have greatly outnumbered those of the B/Victoria lineage.
- Different patterns of dominant type and A subtypes were observed between the countries of the Region.
- While low in numbers, characterized A(H3N2) viruses fell mainly in clade 3C.2a (57%) and subclade 3C.2a1 (42%), while 43% of B/Victoria lineage viruses fell in a subclade of clade 1A viruses that are antigenically distinct from the current trivalent vaccine component.
- The majority of severe cases reported this season were due to influenza virus type B infection and have mostly occurred in persons older than 15 years.
- Mortality from all causes now appears be have returned to normal expected levels in all 20 participating countries and regions that report to EuroMOMO.
- Interim results from 5 European studies indicate 25 to 52% vaccine effectiveness against any influenza.
See all weekly influenza updates
Seasonal influenza is a preventable infectious disease with mostly respiratory symptoms. It is caused by influenza virus and is easily transmitted, predominantly via the droplet and contact routes and by indirect spread from respiratory secretions on hands etc.Read more
Surveillance reports and disease data on seasonal influenza
Latest surveillance reports and disease data on seasonal influenza; Flu News Europe, Influenza virus characterisation reports, ECDC Surveillance Atlas, Annual Epidemiological Reports.Read more