Influenza update

26 January 2015 - Update number 229, based on data up to 11 January 2015


Globally influenza activity was high in the northern hemisphere with influenza A(H3N2) viruses predominating so far this season. Antigenic characterization of most recent A(H3N2) viruses thus far indicated differences from the A(H3N2) virus used in the influenza vaccines for the northern hemisphere 2014-2015. Based on tests to date, the influenza A(H3N2) viruses are expected to be sensitive to neuraminidase inhibitors.

  • In North America, the influenza season was ongoing with still high levels of influenza activity in most countries. Influenza A(H3N2) virus predominated. The influenza activity might have peaked in the USA.
  • In Europe influenza activity was still on the rise with highest activity in the north-western part. Influenza A(H3N2) predominated this season.
  • In northern and western Africa influenza activity seemed to have peaked with influenza B virus predominating, while Egypt reported mainly influenza A(H3N2) detections.
  • In eastern Asia, influenza activity started to decrease with influenza A(H3N2) virus predominating.
  • In central Asia influenza activity remained low.
  • In western Asia, Bahrain and the Islamic Republic of Iran reported mainly influenza A(H1N1)pdm09 activity.
  • In tropical countries of the Americas, influenza activity was low in most countries of the Caribbean, Central America and in the tropical countries of South America.
  • In the southern hemisphere, influenza activity remained at inter-seasonal levels.
  • Based on FluNet reporting (as of 23 January 2015 18:05 UTC), during 2014, week 53 and 2015 week 1 (28 December 2014 to 10 January 2015), National Influenza Centres (NICs) and other national influenza laboratories from 88 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 133 812 specimens. 32 903 were positive for influenza viruses, of which 30 926 (94%) were typed as influenza A and 1977 (6%) as influenza B. Of the sub-typed influenza A viruses, 453 (3.4%) were influenza A(H1N1)pdm09 and 12 678 (96.6%) were influenza A(H3N2). Of the characterized B viruses, 495 (98%) belonged to the B-Yamagata lineage and 10 (2%) to the B-Victoria lineage.

Full influenza update

Seasonal update

For regional updates on influenza see the following links

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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