12 December 2016, - Update number 278, based on data up to 27 November, 2016

Summary

Influenza activity in the temperate zone of the northern hemisphere increased slightly.

• In North America, influenza activity slightly increased with influenza A(H3N2) virus predominating. Influenza-like illness (ILI) levels remained below seasonal thresholds. In the United States, respiratory syncytial virus (RSV) activity continued to be reported.
• In Europe, influenza activity was low but has started to rise, particularly in Northern European countries. Influenza A viruses were predominating with the most frequent subtype being A(H3N2). The season has started earlier than usual with a positivity rate ≥10% for influenza among sentinel surveillance samples.
• In East Asia, influenza activity increased slightly with influenza A(H3N2) remaining the dominant virus circulating.
• In Western Asia influenza detections remained low.
• In Northern Africa, influenza detections increased in Morocco with influenza A(H3N2) viruses dominating.
• In the Caribbean countries, influenza and other respiratory virus activity remained low. In Central America, there was a slight decrease in influenza and other respiratory viruses activity. RSV continued to circulate in Costa Rica.
• In tropical South America, influenza and other respiratory viruses activity remained low with exception of Colombia where RSV activity continued to be reported.
• In Southern Asia, there was a slight increase in influenza detections in both Iran and Sri Lanka with influenza A(H3N2) as the most frequently detected virus in this region.
• In South East Asia, influenza activity continued to be reported at low levels, with influenza A(H3N2) virus predominant in the region. A slight increase in influenza A(H1N1)pdm09 detections was reported in Vietnam.
• In West Africa, influenza detections increased in Ghana with B viruses dominating.
• In Southern Africa, influenza activity continued at inter-seasonal levels.
• In temperate South America, influenza and RSV activity continued to decrease throughout the sub-region.
• In Oceania, influenza virus activity was reported at inter-seasonal levels.
• National Influenza Centres (NICs) and other national influenza laboratories from 80 countries, areas or territories reported data to FluNet for the time period from 14 November 2016 to 27 November 2016 (data as of 2016-12-09 03:37:55 UTC).The WHO GISRS laboratories tested more than 93152 specimens during that time period. 6209 were positive for influenza viruses, of which 5630 (90.7%) were typed as influenza A and 579 (9.3%) as influenza B. Of the sub-typed influenza A viruses, 112 (2.9%) were influenza A(H1N1)pdm09 and 3787 (97.1%) were influenza A(H3N2). Of the characterized B viruses, 46 (36.2%) belonged to the B-Yamagata lineage and 81 (63.8%) to the B-Victoria lineage.