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Influenza Update N° 380

09 November 2020, based on data up to 25 October 2020 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: https://www.who.int/influenza/surveillance_monitoring/updates/Influenza_Transmission_Zones20180914.pdf

Summary

▪ The current influenza surveillance data should be interpreted with caution as the ongoing COVID-19 pandemic have influenced to varying extents health seeking behaviours, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States. The 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. ▪ Globally, despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year. ▪ In the temperate zone of the , influenza activity remained below inter- seasonal levels, though sporadic influenza detections were reported in some countries. ▪ In the temperate zones of the , no influenza detections were reported across countries. ▪ In the and Central American countries, sporadic influenza detections were reported. Severe acute respiratory infection (SARI) activity, likely due to COVID-19, decreased in most reporting countries.

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▪ In tropical , there were no influenza detections across reporting countries. ▪ In tropical , influenza activity was reported in West Africa in Côte d’Ivoire and Niger, and in East Africa in Kenya. ▪ In Southern , influenza activity of predominately influenza A(H3N2) was reported in and India in recent weeks. ▪ In South , influenza detections continued to be reported in Cambodia and Lao People's Democratic Republic (PDR). ▪ Worldwide, of the very low numbers of detections reported, seasonal influenza A(H3N2) viruses accounted for the majority of detections. ▪ National Influenza Centres (NICs) and other national influenza laboratories from 95 countries, areas or territories reported data to FluNet for the time period from 12 October 2020 to 25 October 2020 (data as of 2020-11-06 02:55:12 UTC). The WHO GISRS laboratories tested more than 94 241 specimens during that time period. A total of 140 specimens were positive for influenza viruses, of which 80 (57.1%) were typed as influenza A and 60 (42.9%) as influenza B. Of the sub-typed influenza A viruses, 2 (5.4%) were influenza A(H1N1)pdm09 and 35 (94.6%) were influenza A(H3N2). Of the characterized B viruses, 1 (6.7%) belonged to the B-Yamagata lineage and 14 (93.3%) to the B-Victoria lineage. ▪ During the COVID-19 pandemic, WHO encourages countries to continue routine influenza surveillance, test samples from influenza surveillance sites for influenza and SARS-CoV-2 viruses where resources are available, and report epidemiological and laboratory information in a timely manner to established regional and global platforms (See the Operational considerations for COVID-19 surveillance using GISRS guidance). ______

For more detailed information, see the Influenza reports from WHO Regional Offices:

▪ WHO of the (AMRO): www.paho.org/influenzareports ▪ WHO Region (EMRO): http://www.emro.who.int/health- topics/influenza/situation-update.html ▪ WHO European Region (EURO):www.flunewseurope.org/ ▪ WHO Western Pacific Region (WPRO): www.wpro.who.int/emerging_diseases/Influenza/en/ ▪ EuroMOMO Bulletin: https://www.euromomo.eu

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Countries in the temperate zone of the northern hemisphere

▪ In the temperate zone of the northern hemisphere, influenza activity remained at inter- seasonal level overall. ▪ In the countries of , influenza activity indicators, including the percent of tests positive for influenza, were at very low levels. In the United States of America, at the national level, influenza like illness (ILI) activity remained below the national baseline except in the 0-4 years old, where activity was reported just above the baseline level. The percentage of deaths attributed to pneumonia, influenza or COVID-19 was above the epidemic threshold for pneumonia and influenza mortality established from historical data. In the past few

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weeks, in Canada, influenza testing is reportedly elevated but detections remain low compared to previous seasons. ▪ In , influenza activity remained at inter-seasonal levels though sporadic detections were reported across reporting countries. In France, one influenza A(H3N2) and one influenza B virus detection were reported in hospitalized patients with history of travel to West Africa. Respiratory illness indicators slightly increased across most reporting countries, likely related to SARS-CoV-2 circulation. Rhinovirus activity was reported in some countries performing surveillance for other respiratory viruses. Pooled mortality estimates from the EuroMOMO network showed a slight increase in excess mortality, though limited to a few countries. ▪ In , there were no influenza detections for this reporting period. ▪ In Northern Africa, there were no influenza detections across reporting countries. ▪ In , sporadic influenza detections were reported in recent weeks. ILI activity remained low overall. ▪ In East Asia, influenza illness indicators and influenza activity remained at inter-seasonal levels in most reporting countries. ILI activity appeared to increase in Southern China and was reported at a higher level than the previous three influenza seasons.

Number of specimens positive for influenza by subtype in the northern hemisphere

Data source: FluNet (www.who.int/flunet). Global Influenza Surveillance and Response System (GISRS) Data generated on 06/11/2020 ______

Countries in the tropical zone

Tropical countries of , the Caribbean and South America ▪ In the Caribbean and Central American countries, sporadic influenza detections were reported across reporting countries. Haiti, Jamaica, Costa Rica and Honduras, reported

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decreased SARI activity though levels remained elevated in Costa Rica. Detections of SARS- CoV-2 appeared to decrease in most countries in the sub-region. ▪ In the tropical countries of South America, no influenza detections were reported across reporting countries. SARI activity continued to be reported at high levels in Ecuador, likely related to SARS-CoV-2 circulation.

Tropical Africa ▪ In Western Africa, influenza activity continued to increase in Côte d’Ivoire with co-circulation of influenza A(H3N2) and B-Victoria lineage viruses; influenza detection of predominately influenza A(H1N1)pdm09 were also reported in Niger in recent weeks. ▪ In Middle Africa, there were no influenza updates for this reporting period. ▪ In Eastern Africa, sporadic influenza B detections were reported in Kenya.

Tropical Asia ▪ In Southern Asia, influenza illness indicators and influenza activity of predominately A(H3N2) viruses was reported in Bangladesh in recent weeks. Sporadic influenza A(H3N2) detections continued to be reported in India. ILI and SARI activity increased slightly in Afghanistan and was reported as low across other reporting countries. ▪ In South East Asia, influenza activity of predominately influenza A(H3N2) appeared to decrease in Cambodia. Detections of influenza A(H3N2) continued to be reported in Lao PDR with increased ILI and SARI levels. ______

Countries in the temperate zone of the southern hemisphere

▪ In the temperate zones of the southern hemisphere, influenza activity remained low overall. ▪ In , ILI and other influenza activity indicators remained below usual levels for this time of year in general, despite continued testing. Increased ILI activity was reported in Samoa though the aetiology was not confirmed. Increased ILI activity was also reported in French and likely reflects increased COVID-19 transmission. ▪ In South Africa, no influenza viruses were detected in ILI and pneumonia samples from sentinel sites. Respiratory syncytial virus activity increased in recent weeks and was reported above baseline levels. ▪ In temperate South America, no influenza detections were reported across reporting countries. The number of SARI cases returned below epidemic threshold in Chile and remained at extraordinary level in Paraguay.

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Number of specimens positive for influenza by subtype in southern hemisphere

Data source: FluNet (www.who.int/flunet). Global Influenza Surveillance and Response System (GISRS) Data generated on 06/11/2020

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Sources of data 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.

Seasonal influenza reviews: A review of the 2019 influenza season in the southern hemisphere, was published in January 2020 and can be found here: https://extranet.who.int/iris/restricted/bitstream/handle/10665/330368/WER9501-02-eng-fre.pdf Epidemiological Influenza updates: http://www.who.int/influenza/surveillance_monitoring/updates/latest_update_GIP_surveillance Epidemiological Influenza updates archives 2015: http://www.who.int/influenza/surveillance_monitoring/updates/GIP_surveillance_2015_archives Virological surveillance updates: http://www.who.int/influenza/gisrs_laboratory/updates/summaryreport Virological surveillance updates archives: http://www.who.int/influenza/gisrs_laboratory/updates/

Contact : [email protected]

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