Influenza Update N° 432

Overview

14 November 2022, based on data up to 30 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 increased 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 steeply in recent weeks. Influenza A(H3N2) was predominant among the few subtyped viruses.
• In Europe, overall influenza activity followed an increasing trend but remained relatively low. 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 high influenza activity with B/Victoria-lineage viruses predominating.
• In East Asia, influenza activity of predominantly influenza A(H3N2) remained stable at intermediate levels overall. ​
• In Western Asia influenza activity was elevated. Detections of influenza continued to increase in some countries of the Arabian 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 increased steeply, with elevated activity reported in Bhutan, Iran and Pakistan. The majority of subtyped detections were influenza A(H3N2), followed by A(H1N1)pdm09 and few influenza B detections.
• In South East Asia, detections of predominantly influenza A(H3N2) followed by influenza B and influenza A(H1N1)pdm09 decreased.
• In the temperate zones of the southern hemisphere, overall influenza activity appeared to decrease this reporting period, except in temperate South America where activity increased in several countries.
• In Oceania, influenza activity remained very 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, decreasing detections of influenza B/Victoria and influenza A(H3N2) were reported.
• In temperate South America, influenza detections have continued to increase in Argentina, Chile and Uruguay.  Influenza A(H3N2) viruses predominated in Chile and Uruguay, while influenza B and influenza A(H1N1)pdm09 predominated among subtyped viruses in Argentina.
• National Influenza Centres (NICs) and and other national influenza laboratories from 105 countries, areas or territories reported data to FluNet for the time period from 17 October 2022 to 30 October 2022* (data as of 14/11/2022 15:32:32 AM UTC). The WHO GISRS laboratories tested more than 229940 specimens during that time period. 15723 were positive for influenza viruses, of which 14589 (92.8%) were typed as influenza A and 1134 (7.2%) as influenza B. Of the sub-typed influenza A viruses, 1424 (21.2%) were influenza A(H1N1)pdm09 and 5284 (78.8%) were influenza A(H3N2). Of the characterized B viruses, all 300 (100%) belonged to the B/Victoria lineage.

• COVID-19 positivity from sentinel surveillance increased a little but remained under 10%, after a long-term downtrend beginning in mid-2022. Activity increased sharply in the Region of the Americas, with percent positivity reaching 20%. In the European Region, positivity was stable around 10%. In the Western Pacific Region, positivity declined sharply but remained just above 10%. Positivity declined and was below 10% in all other regions. COVID-19 positivity from non-sentinel surveillance increased to just over 10% due to increased positivity in the South-East Asia and Western Pacific Regions..
• 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 58 countries, areas or territories reported data to FluNet for the time period from six WHO regions (African Region: 9; Region of the Americas: 12; Eastern Mediterranean Region: 3; European Region: 28; South-East Asia Region: 3; Western Pacific Region: 3) reported to FluNet from sentinel surveillance sites for time period from 17 October 2022 to 30 October 2022* (data as of 14/11/2022 15:32:32 AM UTC). The WHO GISRS laboratories tested more than 17395 sentinel specimens during that time period and 1157 (6.7%) were positive for SARS-CoV-2. Additionally, more than 76586 non-sentinel or undefined reporting source samples were tested in the same period and 3761 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.