Influenza virus activity in the world

21 October 2011

Source: Laboratory confirmed data from the Global Influenza Surveillance and Response System (GISRS).

Virological summary #

During weeks 39 to 40 (25 September 2011 to 8 October 2011), overall influenza virus activity was low.

In the southern hemisphere, the number of laboratory confirmed influenza detections continued to decline. Influenza A(H3N2) virus was predominant at low levels in some countries in Americas and Asia, and influenza B in parts of Africa. Influenza A(H1N1)pdm09 activity declined further in Australia and the southern hemisphere in general.

In the northern hemisphere, sporadic influenza virus activity was reported. Influenza A(H3N2) and B viruses were co-circulating in Asia at low levels, while A(H1N1)pdm09 virus detections were reported in some countries in South-east Asia.

Following advice from an expert group, the standardization of terminology of the pandemic A(H1N1) 2009 virus has now been adopted. The official nomenclature is: A(H1N1)pdm09. The announcement can be found on the WHO web at

# Owing to a problem in data transmission between EuroFlu and TESSy, latest information on virology from European Union (EU)/European Economic Area (EEA) Member States is not included in this summary.

During weeks 39 to 40 (25 September 2011 to 8 October 2011), National Influenza Centres (NICs) from 69 countries, areas or territories reported data to FluNet*. A total of 1027 specimens were reported as positive for influenza viruses, 716 (69.7%) were typed as influenza A and 311 (30.3%) as influenza B. Of the sub-typed influenza A viruses reported, 30.2% were influenza A(H1N1)pdm09 and 69.8% were influenza A(H3N2).

(FluNet data as of 18 October 2011 16:15 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)pdm09: Australia, Bolivia (Plurinational State of), Brazil, Cambodia, Cameroon, Chile, China, Kenya, Madagascar, New Zealand, Oman, Panama, United States of America, Viet Nam
  • Influenza A(H1N1) old seasonal virus: no report
  • Influenza A(H3N2): Argentina, Australia, Bolivia (Plurinational State of), Cambodia, Cameroon, Chile, China, Cuba, El Salvador, France, Honduras, India, Kenya, Japan, Lao People's Democratic Republic, New Zealand, Oman, Paraguay, Republic of Korea, South Africa, Thailand, United States of America, Viet Nam
  • Influenza A(H5): no report
  • Influenza B: Australia, Bolivia (Plurinational State of), Burkina Faso, Cambodia, Cameroon, China, Dominican Republic, El Salvador, France, Honduras, India, Japan, Kenya, Lao People's Democratic Republic, Mauritius, New Zealand, South Africa, Tanzania, Thailand, United States of America, Viet Nam
  • No influenza detected: Algeria, Angola, Armenia, Austria, Azerbaijan, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Costa Rica, Ecuador, Estonia, Finland, Georgia, Germany, Ghana, Guatemala, Iceland, Iran (Islamic Republic of), Ireland, Jamaica, Latvia, Lithuania, Malaysia, Mexico, Mongolia, Netherlands, Nicaragua, Norway, Poland, Republic of Moldova, Romania, Russian Federation, Rwanda, Serbia, Slovakia, Slovenia, Spain, Switzerland, Turkey, Ukraine, United Kingdom of Great Britain and Northern Ireland