Summary

Influenza activity in the temperate zone of the northern hemisphere continued to be elevated. Many countries especially in East Asia and Europe appeared to have already peaked and were reporting decreasing trends. Worldwide, influenza A(H3N2) virus was predominant. The majority of influenza viruses characterized so far were similar antigenically to the reference viruses contained in vaccines for use in the 2016-2017 northern hemisphere influenza season. Nearly all tested viruses collected recently for antiviral sensitivity were susceptible to the neuraminidase inhibitor antiviral medications.

• In North America, influenza activity with A(H3N2) virus predominating increased in the United States of America and Mexico, whereas in Canada influenza activity continued to decrease.
• In Europe, influenza activity remained elevated with influenza A (H3N2) virus being the most prominent subtype. Most of the countries reported stable or decreasing trends compared with previous weeks. Persons aged over 65 years were most frequently associated with severe disease from influenza infection.
• In East Asia, influenza activity appeared to be decreasing with influenza A(H3N2) virus predominant.
• In Western Asia, influenza activity was decreasing with influenza A(H3N2) predominant in the region. Low levels of influenza B viruses were also detected.
• In Southern Asia, influenza activity sharply increased in India and Sri Lanka, with mainly influenza A(H1N1)pdm09 reported followed by influenza B and A(H3N2).
• In South East Asia, influenza activity remained low.
• In Northern Africa, influenza activity seemed to have peaked; influenza A(H3N2) and influenza B virus detections were reported.
• In West Africa, influenza B continued to be detected in Ghana.
• In the Caribbean countries and Central America, influenza and other respiratory virus activity remained low in general, except in Puerto Rico where influenza activity remained above the seasonal threshold with influenza A(H3N2) predominating.
• In tropical South America, influenza and other respiratory virus activity remained low, although RSV activity remained elevated in Colombia.
• In the temperate zone of the Southern Hemisphere, influenza activity was at inter-seasonal levels.
• National Influenza Centres (NICs) and other national influenza laboratories from 83 countries, areas or territories reported data to FluNet for the time period from 23 January 2017 to 05 February 2017 (data as of 2017-02-17 11:53:23 UTC).The WHO GISRS laboratories tested more than 154949 specimens during that time period. 40292 were positive for influenza viruses, of which 36922 (91.6%) were typed as influenza A and 3370 (8.4%) as influenza B. Of the sub-typed influenza A viruses, 418 (2.9%) were influenza A(H1N1)pdm09 and 14024 (97.1%) were influenza A(H3N2). Of the characterized B viruses, 332 (62.8%) belonged to the B-Yamagata lineage and 197 (37.2%) to the B-Victoria lineage.