Influenza Update N° 429 - ISS-G20 Laboratorium Repository

03 October 2022, based on data up to 18 September 2022

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)

• The current influenza surveillance data should be interpreted with caution as the ongoing COVID-19 pandemic has influenced to varying extents health seeking behaviours, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States. Various hygiene and physical distancing measures implemented by Member States to reduce SARS-CoV-2 virus transmission have likely played a role in reducing influenza virus transmission. 
• Countries are recommended to monitor the co-circulation of influenza and SARS-CoV-2 viruses. They are encouraged to enhance integrated surveillance and step-up their influenza vaccination campaign to prevent severe disease and hospitalizations associated with influenza. Clinicians should consider influenza in differential diagnosis, especially for high-risk groups for influenza, and test and treat according to national guidance.
• Globally, influenza activity remained low with influenza A(H3N2) viruses predominately detected.
• In the temperate zones of the southern hemisphere, overall influenza activity appeared to further decrease this reporting period, except in South Africa where activity increased.
• In Oceania, influenza detections of primarily influenza A(H3N2) and influenza-like activity (ILI) activity were at low levels overall.  
• In Southern Africa, there was an increase in influenza activity with mainly influenza B viruses reported.
• In the Caribbean and Central American countries, low influenza activity was reported with influenza A(H3N2) most frequently detected.
• In the tropical countries of South America, influenza detections were low and A(H3N2) detections predominated.
• In tropical Africa, influenza activity remained low with influenza A(H3N2) viruses predominant among the reported detections.
• In Southern Asia, influenza detections were predominantly A(H1N1)pdm09 viruses, with influenza A(H3N2) and influenza B viruses also reported.
• In South-East Asia, influenza activity decreased a little, with influenza A(H3N2) viruses predominant.
• In the countries of North America, influenza activity remained at inter-seasonal levels as typically observed at this time of year. Influenza A(H3N2) was predominant among the few subtyped viruses.
• In Europe, overall influenza activity remained at inter-seasonal levels with influenza A(H3N2) detections increasing in a few countries.
• In Central Asia, no influenza detections were reported.
• In Northern Africa, no influenza detections were reported.
• In East Asia, influenza activity of predominantly influenza A(H3N2) continued to decrease in China. Elsewhere, influenza illness indicators and activity were low.
• In Western Asia, detections of influenza slightly increased in some countries of the Arab Peninsula.
• National Influenza Centres (NICs) and and other national influenza laboratories from 99 countries, areas or territories reported data to FluNet for the time period from 05 September 2022 to 18 September 2022* (data as of 2022-09-29 15:56:25 UTC). The WHO GISRS laboratories tested more than 118 327 specimens during that time period. 4123 were positive for influenza viruses, of which 3650 (88.5%) were typed as influenza A and 473 (11.5%) as influenza B. Of the sub-typed influenza A viruses, 369 (13%) were influenza A(H1N1)pdm09 and 2463 (87%) were influenza A(H3N2). Of the characterized B viruses, all (169) belonged to the B-Victoria lineage.
• The WHO Consultation and Information Meeting on the Composition of Influenza Virus Vaccines for Use in the 2023 Southern Hemisphere Influenza Season was held on 19-23 September 2022 in Dublin, Ireland. The recommended composition of influenza virus vaccines for use in the 2023 southern hemisphere influenza season can be consulted at the following link: https://www.who.int/publications/m/item/recommended-composition-of-influenza-virus-vaccines-for-use-in-the-2023-southern-hemisphere-influenza-season.

Entire content available on: https://www.who.int/publications/m/item/influenza-update-n-429