# 5312
Even though levels of ILIs (Influenza-like Illnesses) have dropped well below the baseline level in the UK (see HPA Weekly Influenza Surveillance), influenza activity continues strong across the rest of Europe.
In week 5, once again the 2009 H1N1 virus remains the dominant player, although in some countries influenza B levels are equal to, or even exceed that of the old pandemic strain.
Unlike here in the United States, seasonal H3N2 continues to circulate across Europe in only low levels.
While trends and averages can be established, across the 48 reporting nations covered by the EuroFlu weekly report, there still remains a good deal of variance in activity and virus dominance between nations and regions.
Note: In Europe the acronym SARI is used to denote Severe Acute Respiratory Infection.
Some excerpts (reformatted for readability) from this week’s report:
EuroFlu - Weekly Electronic Bulletin
Week 5 : 31/01/2011-06/02/2011
11 February 2011, Issue N° 388Continued high influenza activity in the WHO European Region
- This issue is based on data reported in week 5/2011 by 48 Member States in the WHO European Region.
- Clinical consultation rates for influenza-like illness (ILI) and/or acute respiratory infections (ARI) are increasing in 27 countries, while 9 others have passed peaks in clinical activity.
- 46% of sentinel specimens from patients with ILI and/or ARI, and 54% of specimens from sentinel SARI patients were positive for influenza in week 5/2011.
- 98% of antigenically characterized viruses from the 2010/2011 influenza season are similar to the viruses included in the 2010/2011 northern hemisphere influenza vaccines.
Current situation – week 5/2011
During week 5/2011, 2 countries (Georgia and Luxembourg) and 3 regions of the Russian Federation reported very high intensity of influenza activity; 6 countries reported high intensity and 25 reported medium intensity. 21 countries reported widespread activity. Of the 25 countries reporting on the impact of influenza on health care systems, 1 (Georgia) reported severe impact; 11 countries reported moderate impact and 13, low impact.
Clinical data also indicated increasing influenza activity in much of the WHO European Region, as 27 countries reported increasing trends in consultation rates for ILI and/or ARI. Some countries in the central, south-eastern and eastern parts of the Region have reported pronounced increases in clinical ILI or ARI activity. In general, the highest consultation rates were reported for children aged 5–14 and 0–4 years.
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Virological situation – week 5/2011
Pandemic influenza A(H1N1) 2009 was reported to be dominant in 17 countries and co-dominant with influenza B in 12 countries.
Influenza B was dominant in 5 countries. During the past few weeks, the predominance of influenza B viruses has increased in countries in western Europe, which had predominantly pandemic A(H1N1) viruses circulating at the start of their season.
In a number of eastern European countries, the earlier predominance of influenza B viruses has now shifted to a predominance of pandemic influenza A(H1N1) 2009 viruses.
Comment
ILI and ARI consultation rates continue to increase in the WHO European Region, particularly in the central, eastern and south-eastern parts, and the percentage of sentinel specimens positive for influenza remains high.
Influenza activity is progressing in a west-to-east manner across the Region, with pandemic influenza A(H1N1) 2009 circulation generally decreasing in the western part of the Region and increasing in the eastern.
Influenza B is becoming relatively more predominant in countries where the prevalence of pandemic influenza A (H1N1) 2009 is decreasing. This shift, with relatively more A(H1N1) 2009 viruses circulating in the eastern part of the Region, may explain the notable difference in the proportion of influenza A to influenza B viruses among SARI patients in week 5/2011, when compared to all SARI viruses for the cumulative 2010/2011 influenza season.
This is because most of the countries conducting sentinel SARI surveillance are in the central and eastern part of the WHO European Region. 98% of antigenically characterized viruses from the 2010/2011 influenza season are similar to the viruses recommended for inclusion in the 2010/2011 northern hemisphere influenza vaccines.
