WHO Global Influenza Update #356

#14,473

While the United States entered its 2019-2020 flu season nearly a month ago - and somewhat unusually with influenza B leading the pack - the majority of the Northern Hemisphere's temperate zone (Europe, Russia, Asia) have yet to report a lot of flu activity.

The World Health Organization's latest bi-weekly global influenza report (#356) - current through November 24th - is beginning to show signs that may be changing.

Of particular interest, while influenza B leads the way in the United States (followed by H1N1 and H3N2), it is A/H3N2 that is most commonly being reported across the rest of the Northern Hemisphere. 

It is not uncommon to see different influenza patterns appear concurrently in different regions of the world. And, while influenza B currently holds sway in the United States, that could change as the flu season progresses.

Influenza update - 356 

09 December 2019 - Update number 356, based on data up to 24 November 2019

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 Transmission Zones pdf, 659kb
Open map in new window png, 254kb
 
Summary

• In the temperate zone of the northern hemisphere, respiratory illness indicators and influenza activity started to increase in most countries. Influenza activity was elevated across the countries in Western Asia.
• In the Caribbean and Central American countries, influenza activity was low overall, except for Jamaica and Honduras. In tropical South American countries, influenza activity remained low
• In tropical Africa, influenza activity remained elevated in some countries of Western Africa.
• In Southern Asia, influenza activity was low across reporting countries, but continued to increase in Iran (Islamic Republic of).
• In South East Asia, influenza activity continued to be reported in Lao PDR and Viet Nam.
• In the temperate zones of the southern hemisphere, influenza activity returned to inter-seasonal levels.
• Worldwide, seasonal influenza A(H3N2) viruses accounted for the majority of detections.
  

National Influenza Centres (NICs) and other national influenza laboratories from 119 countries, areas or territories reported data to FluNet for the time period from 11 November 2019 to 24 November 2019 (data as of 2019-12-06 09:04:10 UTC). The WHO GISRS laboratories tested more than 92883 specimens during that time period. 

• 7914 were positive for influenza viruses, of which 5629 (71.1%) were typed as influenza A and 2285 (28.9%) as influenza B.

• Of the sub-typed influenza A viruses, 2682 (71.5%) were influenza A(H3N2) and 1069 (28.5%) were influenza A(H1N1)pdm09.

• Of the characterized B viruses, 1014 (96.8%) belonged to the B-Victoria lineage and 34 (3.2%) to the B-Yamagata lineage.

Detailed influenza update

Download PDF pdf, 895kb