The latest WHO global influenza surveillance report is out (dated Apr 2nd), and while much of the Northern Hemisphere is enjoying a welcomed drop in flu activity - as noted last Friday in Russia's Late Season Flu Surge Continues - some regions, including parts of Eastern Europe, are seeing increasing rates of flu.
Note: For the purposes of these reports, the WHO places the Russian Federation into the Eastern Europe zone; which also includes Belarus, Bulgaria, Czech Republic, Hungary, Poland, Republic of Moldova, Romania, Slovakia, and Ukraine.
As noted last week, while a late season surge in influenza in Russia isn't unheard of, it does go against the pattern of the last twenty years (see Eurosurveillance: Changes In Timing Of Influenza Epidemics - WHO European Region 1996-2016), which have tended to peak earlier with each passing year.
Of particular note, among sub-typed Influenza A viruses in this latest report, A/H1N1 (at 64%) has surged well ahead of A/H3N2, which just 3 months ago led the pack at nearly 70%.
Whether this trend carries forward into the Southern Hemisphere is something we'll be watching keenly over the coming months.Some excerpts from this latest report:
02 April 2018 - Update number 312, based on data up to 18 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 appeared to decrease 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, inluenza 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 05 March 2018 to 18 March 2018 (data as of 2018-03- 30 04:46:41 UTC).The WHO GISRS laboratories tested more than 206175 specimens during that time period. 50579 were positive for influenza viruses, of which 23651 (46.8%) were typed as influenza A and 26928 (53.2%) as influenza B.
Of the sub-typed influenza A viruses, 6313 (64%) were influenza A(H1N1)pdm09 and 3552 (36%) were influenza A(H3N2). Of the characterized B viruses, 3184 (91%) belonged to the B-Yamagata lineage and 316 (9%) to the B-Victoria lineage.
Detailed influenza update