Weekly influenza surveillance overview, April 20 2012 - Week 15

Surveillance report

20 April 2012

The weekly/bi-weekly influenza surveillance overview is a collection of timely and relevant information regarding influenza activity in Europe. It provides key statistical data on a variety of issues including the following: sentinel surveillance of influenza-like illness (ILI) and acute respiratory illness (ARI); virological surveillance; hospital surveillance of severe acute respiratory infection (SARI); mortality surveillance and qualitative reporting. An up-to-date report is available on Fridays.

Executive Summary

The reported national influenza trends indicate that seasonal influenza is on the decline all across Europe.

The 2011–2012 influenza season started late and has been without any clear geographic progression. During week 15/2012, low intensity was reported in 23 countries, with decreasing trends in 14 countries. Of those, 13 countries reported decreasing trends for two consecutive weeks, suggesting that their influenza seasons have peaked.

Virological surveillance for week 15/2012 shows that of 302 sentinel specimens tested, 29.1% were positive for influenza virus. This proportion has decreased for seven consecutive weeks from a peak of nearly 60% in week 8. Of the 88 positive specimens from the sentinel sources 30 (34%) were type B. As expected towards the end of the season, this proportion has been steadily rising. This suggests that now around a third of circulating influenza viruses are type B.

Since week 40/2011, a total of 1 710 severe cases in hospital, mostly influenza related, including 101 fatalities, have been reported by seven countries.

Publication file

120420_SUR_Weekly_Influenza_Surveillance_Overview.pdf

English (1.76 MB - PDF)

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