Influenza Update N° 431

Overview

31 October 2022, based on data up to 16 October 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)

• Countries are recommended to monitor the co-circulation of influenza and SARS-CoV-2 viruses. They are encouraged to enhance integrated surveillance, and in northern 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 guidance.
• Globally, influenza activity remained low and where subtyped, influenza A(H3N2) viruses predominated. An increasing trend of influenza activity was observed in the northern hemisphere while a plateau was observed in the southern hemisphere.
• In the countries of North America, influenza activity increased slightly in recent weeks. Influenza A(H3N2) was predominant among the few subtyped viruses.
• In Europe, overall influenza activity remained at inter-seasonal levels, with a low but increasing trend. Influenza A viruses predominated among the reported detections in general with A(H3N2) viruses accounting for the majority of subtyped influenza A viruses.
• In central Asia, Kazakhstan reported increased influenza activity with B/Victoria-lineage viruses predominating.
• In East Asia, influenza activity of predominantly influenza A(H3N2) remained stable, at low levels, overall. ​
• In Western Asia influenza activity was elevated. Detections of influenza continued to increase in some countries of the Arab Peninsula.
• 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 detections of influenza A(H3N2), B/Victoria and A(H1N1)pdm09 reported .
• In Southern Asia, influenza activity remained low, with the exception of Iran (Islamic Republic of) where increased activity was reported. The majority of subtyped detections were influenza A(H3N2) and A(H1N1)pdm09, with few influenza B detections.
• In the temperate zones of the southern hemisphere, overall influenza activity appeared to further decrease this reporting period, except in temperate South America where activity increased in some countries.
• In Oceania, influenza activity remained low with detections of influenza A(H1N1)pdm09 and influenza A(H3N2) and some B viruses in Australia. ILI activity in New Zealand and, in general, across the Pacific Islands remained low except in a few countries.
• In Southern Africa, influenza detections decreased. Influenza B/Victoria viruses predominated, with some influenza A(H3N2) and only very few influenza A(H1N1)pdm09 virus detections.
• In temperate South America, influenza detections have continued to increase in Argentina and Chile. Elsewhere, influenza activity remained low or below the seasonal threshold. Influenza A viruses predominated with A(H1N1)pdm09 predominant among subtyped viruses in Argentina and other countries reporting mostly A(H3N2) viruses. 
• National Influenza Centres (NICs) and other national influenza laboratories from 113 countries, areas or territories reported data to FluNet for the time period from 03 October 2022 to 16 October 2022* (data as of 10/28/2022 7:17:42 AM UTC). The WHO GISRS laboratories tested more than 311623 specimens during that time period. 13035 were positive for influenza viruses, of which 11782 (90.39%) were typed as influenza A and 1278 (9.80%) as influenza B. Of the sub-typed influenza A viruses, 872 (18.05%) were influenza A(H1N1)pdm09 and 3958 (81.95%) were influenza A(H3N2). Of the characterized B viruses, all 423 were of the B/Victoria lineage. 

• COVID-19 positivity from sentinel surveillance increased above 10% during the latest week of reporting, after a long-term downtrend beginning in mid-2022. Activity fluctuated across all WHO regions except for the Region of the Americas of WHO where the trend continued to decrease. COVID-19 positivity from non-sentinel surveillance increased from 4% to 17% during the latest week of the reporting period.
• 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://www.who.int/publications/i/item/WHO-2019-nCoV-integrated_sentinel_surveillance-2022.1.
• National Influenza Centres (NICs) and other national influenza laboratories from 68 countries, areas or territories reported data to FluNet for the time period from six WHO regions (African Region: 13; Region of the Americas: 16; Eastern Mediterranean Region: 4; European Region: 30; South-East Asia Region: 3; Western Pacific Region: 2 ) reported to FluNet from sentinel surveillance sites for time period from 03 October 2022 to 16 October 2022* (data as of 10/28/2022 7:17:42 AM UTC). The WHO GISRS laboratories tested more than 34652 sentinel specimens during that time period and 2070 (5.97%) were positive for SARS-CoV-2. Additionally, more than 232924 non-sentinel or undefined reporting source samples were tested in the same period and 11380 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.