Weekly influenza surveillance overview, January 25, 2013 - Week 3

Surveillance report

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 and acute respiratory illness; virological surveillance; hospitalised laboratory-confirmed influenza cases; mortality surveillance and qualitative reporting. An up-to-date report is available on Fridays. This report was amended on 25 January 2013.

Executive summary

Influenza activity remains high and increasing in many European countries, although transmission may have peaked in some countries, mostly in western Europe, concludes the Weekly Influenza Surveillance Overview, Week 3, 2013.

Thirteen European countries as well as one region in the UK (Northern Ireland) reports medium intensity of influenza transmission, and one country (Iceland) reports high intensity. Seventeen countries reports increasing transmission, compared to 19 countries in week 2/2013. At the same time, five countries, mostly in western Europe, are reporting decreasing trends, compared to only two countries in week 02/2013, indicating that transmission may have peaked in these countries.

Virological surveillance in week 3 shows that, of the 1629 sentinel specimens tested, 42.2% were positive for influenza virus. This relatively high percentage is similar to what was seen in the two previous weeks.

Since week 40/2012, of all influenza virus detections in sentinel specimens, the proportion of type A and B viruses has been almost equal, 50:50. Of influenza A viruses subtyped, 42% were A(H3) and 58% were A(H1). The virological pattern seen in Europe is different from that being reported in North America where A(H3) viruses are dominant.

ECDC continues to monitor and report influenza activity in Europe on weekly basis throughout the season.