Weekly influenza update, week 15, April 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.
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Summary
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Influenza viruses continued to circulate in the Region with 26% of the individuals sampled from primary healthcare settings testing positive, while all countries reported low or medium intensity of activity of respiratory infections.
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Both influenza virus types A and B were co-circulating with the majority being type A viruses.
2017/18 season overview
- Influenza has been circulating widely in the Region since week 52/2017, based on increased proportions of sentinel specimens testing positive for influenza viruses in all countries of the Region up to week 15, which is longer than in recent seasons and may contribute to the severity of this season.
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For the Region overall, 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. Click here for more information
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Different patterns of dominant type and A subtypes were observed between the countries of the Region. By week 15, influenza A viruses were dominant in several eastern European countries.
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Of the type A virus detections from sentinel sources, the majority of which were subtyped, A(H1N1)pdm09 viruses have outnumbered A(H3N2) viruses. In non-sentinel sources, similar numbers of A(H3N2) viruses and A(H1N1)pdm09 viruses were reported. Click here for more information
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While low in number, 55% of characterized A(H3N2) viruses belong to clade 3C.2a, 42% to clade 3C.2a1 and 41% of B/Victoria lineage viruses belong to a subclade of clade 1A viruses that are antigenically distinct from the current trivalent vaccine component. Click here for more information
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The majority of severe cases reported this season are due to influenza type B and have mostly occurred in persons older than 15. Click here for more information
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Mortality from all causes based on pooled data from 22 EU countries and regions that reported to EuroMOMO remained elevated in some countries. Click here for more information
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Interim results from 5 European studies indicate 25 to 52% vaccine effectiveness against any influenza. Click here for more information
