Influenza update

20 December 2013 - Update number 201


  • In North America the influenza season has started. The predominant subtype of influenza viruses detected was influenza A(H1N1)pdm09.
  • For the rest of the northern hemisphere as well as in the southern hemisphere influenza activity remained low.
  • In countries of tropical areas variable influenza activity was reported.
  • Based on FluNet reporting (as of 19 December 2013, 07:15 UTC), during weeks 48 to 49 (24 November 2013 to 7 December 2013), National Influenza Centres (NICs) and other national influenza laboratories from 89 countries, areas or territories reported influenza surveillance data. The WHO GISRS laboratories tested more than 42 360 specimens. 3304 were positive for influenza viruses, of which 2816 (85.3%) were typed as seasonal influenza A and 487 (14.7%) as influenza B. Of the sub-typed seasonal influenza A viruses, 1166 (66.4%) were influenza A(H1N1)pdm09and 591 (33.6%) were influenza A(H3N2). Of the characterized B viruses, 39 (70.9%) belonged to the B-Yamagata lineage and 16 (29.1%) to the B-Victoria lineage.

Full influenza update

For updates on the influenza at the human-animal interface see the following WHO web pages:

Source of data

The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks.
The updates are based on available epidemiological and virological data sources, including FluNet (reported by the WHO Global Influenza Surveillance and Response System) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.


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