Influenza update - 311

19 March 2018 - Update number 311, based on data up to 4 March 2018

Information in this report is categorized by influenza transmission zones, which are geographical groups of countries, areas or territories with similar influenza transmission patterns. For more information on influenza transmission zones, see the link below


Influenza activity remained high but appeared to have peaked in some countries in the temperate zone of the northern hemisphere. In the temperate zone of the southern hemisphere activity remained at inter-seasonal levels. Worldwide, influenza A and influenza B accounted for a similar proportion of influenza detections.

National Influenza Centres (NICs) and other national influenza laboratories from 111 countries, areas or territories reported data to FluNet for the time period from 19 February 2018 to 04 March 2018 (data as of 2018-03-16 03:54:19 UTC).The WHO GISRS laboratories tested more than 24 8161 specimens during that time period. 72 543 were positive for influenza viruses, of which 32 650 (45%) were typed as influenza A and 39 893 (55%) as influenza B. Of the sub-typed influenza A viruses, 7350 (60.4%) were influenza A(H1N1)pdm09 and 4817 (39.6%) were influenza A(H3N2). Of the characterized B viruses, 4820 (94.7%) belonged to the B-Yamagata lineage and 269 (5.3%) to the B-Victoria lineage.

Detailed influenza update

Influenza fact sheet

Seasonal update

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), FluID (epidemiological data reported by national focal points) 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.