Influenza Update N° 448

Overview

26 June 2023, based on data up to 11 June 2023

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)

• Countries are recommended to monitor the relative co-circulation of influenza and SARS-CoV-2 viruses and report to RespiMART (FluNet and FluID) directly or via regional platforms. They are encouraged to enhance integrated surveillance and in southern hemisphere countries 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 and WHO guidance.
• Globally, influenza detections remained low, but in the southern hemisphere, some countries reported variable changes in influenza detections in recent weeks while detections in other countries seemed to have peaked.
• In Oceania, influenza activity continued to increase with influenza A viruses predominant.
• In South Africa, influenza activity decreased but remained at a moderate level in pneumonia and decreased to a low level in influenza-like illness (ILI) surveillance with influenza A viruses predominately detected.
• In temperate South America, influenza activity appeared to decrease with A(H1N1)pdm09 viruses most frequently detected followed by B viruses, mainly reflecting an apparent decrease in Chile. Variable activity was reported in other countries.
• In the Caribbean countries, influenza activity remained low overall. In the Central American countries, increased influenza activity was reported in a few countries with A(H1N1)pdm09 most frequently detected followed by B/Victoria lineage viruses.
• overall influenza activity decreased with detections of predominantly A(H1N1)pdm09 and B viruses. 
• In tropical Africa, influenza detections were low in reporting countries. Influenza A(H1N1)pdm09 viruses predominated among reported detections.
• In Southern Asia, influenza activity remained low with all seasonal subtypes detected.
• In South-East Asia, influenza activity remained stable in most reporting countries, with continued reporting of predominantly A(H1N1)pdm09 and A(H3N2) virus detections.
• In the temperate zones of the northern hemisphere, influenza activity was reported at low levels or below seasonal threshold in most reporting countries. All seasonal influenza subtypes were detected in similar proportions overall.
• Globally, RSV activity was generally low except in Australia and a few countries in the Region of the Americas. RSV activity increased in a few countries in tropical and temperate South America.
• National Influenza Centres (NICs) and other national influenza laboratories from 108 countries, areas or territories reported data to FluNet for the time period from 29 May 2023 to 11 June 2023* (data as of 23/06/2023 07:09:51 AM UTC). The WHO GISRS laboratories tested more than 262 237 specimens during that time period. 6709 were positive for influenza viruses, of which 4221 (62.9%) were typed as influenza A and 2488 (37.1%) as influenza B. Of the sub-typed influenza A viruses, 2009 (73.6%) were influenza A(H1N1)pdm09 and 719 (26.4%) were influenza A(H3N2). Of the type B viruses for which lineage was determined, all (321) belonged to the B/Victoria lineage.

• Globally, SARS-CoV-2 positivity from sentinel surveillance decreased to 15%. Activity decreased to approximately 25% in the Western Pacific region and remained around 13% in the Region of the Americas. Activity was around or below 10% in the other regions. SARS-CoV-2 positivity from non-sentinel surveillance was reported around 16% globally. 
  
• 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. The guidance can be found here: https://www.who.int/publications/i/item/WHO-2019-nCoV-integrated_sentinel_surveillance-2022.1.
• National Influenza Centres (NICs) and other national influenza laboratories from 73 countries, areas or territories from six WHO regions (African Region: 12; Region of the Americas: 20; Eastern Mediterranean Region: 4; European Region: 26; South-East Asia Region: 5; Western Pacific Region: 6) reported to FluNet from sentinel surveillance for time period from 29 May 2023 to 11 June 2023* (data as of 23/06/2023 07:09:51 AM UTC). The WHO GISRS laboratories tested more than 36 666 sentinel specimens during that time period and 6291 (17.2%) were positive for SARS‑CoV-2. Additionally, more than 61 306 non-sentinel or undefined reporting source samples were tested in the same period and 8660 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.