Influenza update - 313

16 April 2018 - Update number 313, based on data up to 01 April 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 decreased in most of the countries in the temperate zone of the northern hemisphere, with exception of Eastern Europe where activity continued to increase. In the temperate zone of the southern hemisphere, influenza 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 107 countries, areas or territories reported data to FluNet for the time period from 19 March 2018 to 01 April 2018 (data as of 2018-04-13 03:50:07 UTC).The WHO GISRS laboratories tested more than 171054 specimens during that time period. 34751 were positive for influenza viruses, of which 18186 (52.3%) were typed as influenza A and 16565 (47.7%) as influenza B. Of the sub-typed influenza A viruses, 4763 (62.7%) were influenza A(H1N1)pdm09 and 2839 (37.3%) were influenza A(H3N2). Of the characterized B viruses, 1704 (91%) belonged to the B-Yamagata lineage and 169 (9%) 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.