Influenza

Influenza update

12 January 2015 - Update number 228

Summary

Globally influenza activity continued to increase in the northern hemisphere with influenza A(H3N2) viruses predominating so far this season. Antigenic characterization of most recent A(H3N2) viruses so far indicated differences from the A(H3N2) virus used in the influenza vaccines for the northern hemisphere 2014-2015. The tested influenza A(H3N2) viruses so far did show sensitivity to neuraminidase inhibitors.

  • In North America, the influenza season was ongoing with influenza activity still increasing in most areas. Influenza A(H3N2) was the predominant virus.
  • In Europe influenza activity was still low, but the season seemed to have started.
  • In eastern Asia, influenza activity increased with influenza A(H3N2) virus predominated.
  • In northern and western Africa influenza activity increased with influenza B virus predominant.
  • In tropical countries of the Americas, influenza activity increased in some countries of the Caribbean, decreased in Central America and was low in the tropical countries of South America.
  • In tropical Asia, influenza activity increased slightly but remained low with influenza B predominating.
  • In the southern hemisphere, influenza activity remained at low levels, though ILI activity remained high in several Pacific Islands.
  • Based on FluNet reporting (as of 9 January 2015 13:00 UTC), during weeks 51 to 52 (14 December 2014 to 27 December 2014), National Influenza Centres (NICs) and other national influenza laboratories from 80 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 96 535 specimens. 23 421 were positive for influenza viruses, of which 22 129 (94.5%) were typed as influenza A and 1292 (5.5%) as influenza B. Of the sub-typed influenza A viruses, 163 (1.7%) were influenza A(H1N1)pdm09 and 9211 (98.3%) were influenza A(H3N2). Of the characterized B viruses, 423 (97.9%) belonged to the B-Yamagata lineage and 9 (2.1%) 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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