Influenza activity was widespread in four countries in week 4 and present or increasing in the rest of Europe. The subtype A(H3N2) is dominating the season to date but A(H1) and B viruses are also present. This is reported in the latest edition of the ECDC Weekly influenza surveillance report (WISO).
During 04/2012 increased geographic spread was reported by 23 of 27 countries and increasing trends by 12 countries. The epidemic threshold was exceeded significantly in the four countries Bulgaria, Iceland, Italy and Spain - and was just above threshold in Romania and Sweden.
The subtype A(H3N2) is dominating the season to date but A(H1) and B viruses are also present. Of 469 sentinel specimens testing positive for influenza, 95.7% were type A and 4.3% were type B. Of 650 influenza A viruses subtyped, including some from non sentinel sources, 96.6% were A(H3) and 3.4% were A(H1)pdm09. In the limited number of specimens that were tested for antiviral resistance, no antiviral resistance to the neuraminidase inhibitors (oseltamivir and zanamivir) was found.
Cumulatively this season, there have been 333 cases of severe acute respiratory infections reported by 6 countries. Where typing and subtyping had been performed, 16% were associated with A(H1)pdm09, 75% with A(H3) and 9% with type B.
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