Influenza Update N° 420 - ISS-G20 Laboratorium Repository

Overview

30 May 2022, based on data up to 15 May 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. 
• Globally, influenza activity continued to decrease, following a peak in March 2022.
• Countries are recommended to prepare for the co-circulation of influenza and SARS-CoV-2 viruses. They are encouraged to enhance integrated surveillance to monitor influenza and SARS-CoV-2 at the same time, 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.
• In the temperate zones of the northern hemisphere, influenza activity decreased or remained stable. Detections were mainly influenza A(H3N2) viruses and B/Victoria lineage viruses, with some detections of A(H1N1)pdm09 viruses.
• In the countries of North America, influenza activity was stable compared to the previous period and influenza positivity was higher than usual for this time of year. Activity was predominantly due to influenza A viruses, with A(H3N2) predominant among the subtyped viruses. Respiratory syncytial virus (RSV) activity remained low in the United States of America (USA) and Canada. 
• In Central Asia, no influenza detections were reported.
• In Europe, overall influenza continues to decline with influenza A(H3N2) predominant.
• In East Asia, detections of influenza B (Victoria lineage) viruses continued to decrease in China while influenza A(H3N2) detections increased in the Southern Provinces to make influenza A (H3N2) the predominantly detected virus in China. Elsewhere, influenza illness indicators and activity remained low. 
• In Northern Africa, Tunisia reported a single influenza A (H3N2) detection.
• In Western Asia, influenza activity was low across reporting countries except Georgia and Qatar where elevated detections of influenza A (H3N2) and mainly influenza A(H3N2) and some influenza A(H1N1)pdm09 and B viruses were reported respectively.
• In the Caribbean and Central American countries, low influenza activity was reported with influenza A(H3N2) predominant.
• In tropical South America, low influenza activity was reported with influenza A(H3N2) predominant.
• In tropical Africa, influenza activity remained low with influenza A(H3N2) predominating followed by influenza B/Victoria lineage viruses.
• In Southern Asia, influenza virus detections were at low levels with a few influenza A(H3N2), A(H1N1)pdm09 viruses and influenza B detections. 
• In South-East Asia, sporadic detections of influenza A(H3N2) were reported in Singapore and sporadic influenza A and B detections were reported in Malaysia.
• In the temperate zones of the southern hemisphere, influenza activity was low overall, except in Argentina and Chile. Influenza detections increased in South Africa and Australia. RSV activity increased in parts of Australia and temperate South America and remained at moderate levels in South Africa.
• National Influenza Centres (NICs) and other national influenza laboratories from 111 countries, areas or territories reported data to FluNet for the time period from 02 May 2022 to 15 May 2022* (data as of 2022-05-273 06:57:14 UTC). The WHO GISRS laboratories tested more than 224 033 specimens during that time period. 23 784 were positive for influenza viruses, of which 23 393 (98.4%) were typed as influenza A and 394 (1.6%) as influenza B. Of the sub-typed influenza A viruses, 153 (4.3%) were influenza A(H1N1)pdm09 and 3427 (95.7%) were influenza A(H3N2). Of the characterized B viruses, all 129(100%) belonged to the B-Victoria lineage.

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.

• Overall COVID positivity from sentinel surveillance increased during the reporting period to 13%. The highest increases were observed in the African Region of WHO where positivity was around 20% and in the Region of the Americas of WHO where positivity was around 15%. Activity from non-sentinel sites was varied. Positivity was below 10% overall and in all reporting regions except in the Western Pacific Region of WHO where positivity was above 30% and the South-East Asia Region of WHO where positivity decreased but remained high at 24.8%. Positivity increased in the African Region and Eastern Mediterranean Region and fluctuated around 10% in the Region of the Americas.
• National Influenza Centres (NICs) and other national influenza laboratories from 46 countries, areas or territories and six WHO regions (African Region: 1;  Region of the Americas: 16;  Eastern Mediterranean Region: 3;  European Region: 18;  South-East Asia Region: 4;  Western Pacific Region: 4) reported to FluNet from sentinel surveillance sites for time period from 02 May 2022 to 15 May 2022* (data as of 2022-05-27 06:57:14 UTC). The WHO GISRS laboratories tested more than 31 755 sentinel specimens during that time period and 4118 (13%) were positive for SARS-CoV-2. Additionally, more than 463 147 non-sentinel or undefined reporting source samples were tested in the same period and 51 161 were positive for SARS-CoV-2. Further details are included at the end of this update.

Entire content available on: https://www.who.int/publications/m/item/influenza-update-n-420