16 April 2018 - Update number 313, based on data up to 01 April 2018

Summary

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.