Influenza Update N° 429

3 October 2022
 | Emergency situation update
Influenza Update N° 429
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Overview

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://covid.comesa.int/publications/m/item/recommended-composition-of-influenza-virus-vaccines-for-use-in-the-2023-southern-hemisphere-influenza-season.

During the COVID-19 pandemic, WHO encourages countries, especially those that have received the multiplex influenza and SARS-CoV-2 reagent kits from GISRS, to conduct integrated surveillance of influenza and SARS-CoV-2 and report epidemiological and laboratory information in a timely manner to established regional and global platforms. Revised interim guidance has just been published here: https://covid.comesa.int/publications/i/item/WHO-2019-nCoV-integrated_sentinel_surveillance-2022.1.

  • COVID-19 positivity from sentinel surveillance continued to decrease and was below 10%. A decreasing trend was observed across all WHO regions except for the African Region were positivity increased compared to the previous reporting period though remaining below 10%. Similarly, COVID-19 positivity from non-sentinel surveillance continued also to decline to below 10%.
  • National Influenza Centres (NICs) and other national influenza laboratories from 53 countries, areas or territories from six WHO regions (African Region: 9; Region of the Americas: 17; Eastern Mediterranean Region: 1; European Region: 20; South-East Asia Region: 3; Western Pacific Region: 3) reported to FluNet from sentinel surveillance sites for time period from 05 Sep 2022 to 18 Sep 2022* (data as of 2022-09-29 15:56:25 UTC). The WHO GISRS laboratories tested more than 36 200 sentinel specimens during that time period and 3 828 (10.6%) were positive for SARS-CoV-2. Additionally, more than 330 202 non-sentinel or undefined reporting source samples were tested in the same period and 32 114 were positive for SARS-CoV-2. Further details are included at the end of this update.

Source of data

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The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks. The updates are based on available epidemiological and virological data sources, including FluNet (reported by the WHO Global Influenza Surveillance and Response System), FluID (epidemiological data reported by national focal points) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.

*It includes data only from countries reporting on positive and negative influenza specimens.

 

WHO Team
Global Influenza Programme (GIP)