Influenza virus activity in the world
6 May 2011
Virological summary
During weeks 15 to 16 (10 April 2011 to 23 April 2011), low numbers of laboratory confirmed detections of influenza A(H1N1)2009, A(H3N2) and B viruses continued to be reported globally with only a few countries reporting regional or local outbreaks of influenza.
Data reported to FluNet over this time period indicated that the proportion of influenza B viruses continued to increase relative to influenza A viruses, particularly in Canada and parts of Asia and Europe. Influenza A(H1N1)2009 was the predominant virus in some countries in Central and South America. Influenza A(H3N2) was the most prevalent virus in a few countries such as Brazil, Democratic Republic of the Congo, Guatemala and Rwanda. In the southern hemisphere and most tropical regions, influenza activity due to A(H1N1)2009, A(H3N2) and B viruses remained low. The Dominican Republic however continued to experience outbreaks of A(H1N1)2009 virus.
The vast majority of recently characterized viruses remain antigenically similar to the WHO recommended vaccines for the 2010-2011 northern hemisphere and 2011 southern hemisphere influenza seasons.
During weeks 15 to 16, National Influenza Centres (NICs) from 68 countries, areas or territories reported data to FluNet*. A total of 2 012 specimens were reported as positive for influenza viruses, 791 (39.3%) were typed as influenza A and 1 221 (60.7%) as influenza B. Of the sub-typed influenza A viruses reported, 46.8% were influenza A(H1N1)2009 and 52.7% were influenza A(H3N2).
(FluNet data as of 3 May 2011 15:00 UTC)
* Some NICs report to FluNet retrospectively leading to updates of previous summary data.
Influenza virus detection by type/subtype in countries, areas or territories:
- Influenza A(H1N1)2009: Algeria, Australia, Austria, Belarus, Bulgaria, Cameroon, Canada, China, Colombia, Czech Republic, Denmark, Dominican Republic, Estonia, France - French Guiana, Georgia, Ghana, India, Iran (Islamic Republic of), Italy, Jamaica, Japan, Kenya, Mexico, Norway, Panama, Poland, Romania, Russian Federation, Slovakia, South Africa, Sri Lanka, Sweden, Switzerland, Thailand, Tunisia, United States of America, Viet Nam
- Influenza A(H1N1) (old seasonal virus): China
- Influenza A(H3N2): Algeria, Australia, Brazil, Canada, China, Colombia, Cuba, Democratic Republic of the Congo, France, France - French Guiana, Ghana, Guatemala, Iran (Islamic Republic of), Japan, Latvia, Madagascar, Mexico, Russian Federation, Rwanda, Serbia, Spain, Sweden, Thailand, Turkey, United States of America, Viet Nam
- Influenza A(H5): no report
- Influenza B: Algeria, Australia, Austria, Belarus, Belgium, Brazil, Bulgaria, Canada, China, Costa Rica, Croatia, Cuba, Czech Republic, Denmark, Ethiopia, Estonia, Finland, France, Georgia, Germany, Ghana, Greece, Hungary, Iceland, India, Iran (Islamic Republic of), Italy, Jamaica, Japan, Kenya, Lao People's Democratic Republic, Latvia, Madagascar, Mali, Mexico, Norway, Poland, Romania, Russian Federation, Serbia, Slovakia, South Africa, Spain, Sri Lanka, Sweden, Switzerland, Tunisia, Turkey, United Kingdom of Great Britain and Northern Ireland, United States of America, Viet Nam
- No influenza activity reported: Afghanistan, Albania, Argentina, Armenia, Austria, Azerbaijan, Bosnia and Herzegovina, Central African Republic, Ecuador, France - Guadeloupe, France - Martinique, Honduras, Luxembourg, Malta, Mauritius, Mongolia, Morocco, Netherlands, Norway, Paraguay, Portugal, Romania, Slovenia
