# 5293
While the flu has subsided in the UK, and shows signs of decline in Canada, it continued to rise in the United States and much of Europe during the latest reporting period (week 4).
Unlike what we’ve seen in the United States, where the seasonal H3N2 virus has been the big player, in Europe it is the 2009 H1N1 virus that predominates.
This week the ECDC and EuroFlu both take notice of a growing number of H1N1 virus samples showing an H185T substitution in the HA segment. Here is the EuroFlu Statement:
Since the genetic characterization algorithms were put in place for pandemic influenza A(H1N1) viruses at the start of the 2010/2011 influenza season, a new genetic subgroup has been observed to emerge that is geographically dispersed and increasing in prevalence.
This genetic subgroup is characterized by an S185T substitution in HA and is represented by A/England/142/2010.
To date, viruses carrying the S185T substitution remain antigenically similar to the current vaccine virus A/California/7/2009.
At present, 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.
The clinical significance of this H185T substitution (if any) isn’t immediately apparent.
Thus far, we are assured that it doesn’t affect this year’s vaccine effectiveness, and that 98% of all flu viruses tested this winter are a good match to the vaccine.
Influenza Intensity map – week 4.
EuroFlu - Weekly Electronic Bulletin
High influenza activity across the European Region
This week, the EuroFlu bulletin introduces data from sentinel surveillance systems on severe acute respiratory infections (SARI). A footnote gives more information on the minimum criteria for surveillance systems reporting SARI data on the EuroFlu platform.
This issue is based on data reported in week 4/2011 by 47 Member States in the WHO European Region. Influenza activity is increasing in most countries in the Region, and 23 report widespread influenza activity. 46% of sentinel specimens from patients with influenza-like illness (ILI) and/or acute respiratory infections (ARI), and 44% of specimens from hospitalized SARI patients were positive for influenza in week 4/2011. At present, 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 4/2011
During week 4/2011, 2 countries (Georgia and Luxembourg) reported very high intensity of influenza activity; 8 reported high intensity, and 26 reported medium intensity. The geographical spread of influenza activity was reported to be widespread in 23 countries. Of the 25 countries reporting on the impact of influenza on health care systems, 1 (Georgia) reported severe impact, 10 countries reported moderate impact and 14, low impact.Clinical data also indicated increasing influenza activity in much of the WHO European Region, as 31 countries reported increasing trends in consultation rates for ILI and/or ARI. In general, the highest consultation rates were reported for children aged 0–4 and 5–14 years. In contrast, declining clinical trends in ILI were observed in Ireland and the United Kingdom, and some southern countries (Israel, Malta, Portugal and Spain).
Seven countries (Georgia, Kyrgyzstan, Romania, the Republic of Moldova, the Russian Federation, Serbia and Ukraine) reported clinical data on SARI from sentinel hospitals. Hospitalizations due to SARI have increased during recent weeks in Georgia, Kyrgyzstan, Romania, the Russian Federation and Serbia, which also reported increases in clinical consultation rates for ILI or ARI.
Virological situation – week 4/2011
Pandemic influenza A(H1N1) 2009 continued to predominate in the Region. It was reported to be dominant in 19 countries and co-dominant with influenza B in 13 countries. Influenza B was dominant in 4 countries.
