Influenza Update N° 423 - ISS-G20 Laboratorium Repository

Overview

11 July 2022, based on data up to 26 June 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. 
• Countries are recommended to monitor the co-circulation of influenza and SARS-CoV-2 viruses. They are encouraged to enhance integrated surveillance 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.
• Global influenza activity has remained stable, following a decreasing trend from a peak in March 2022.
• In the temperate zones of the southern hemisphere, overall influenza activity appeared to plateau after increasing in recent weeks. 
• In Southern Africa, influenza activity stabilized, with the majority of detections reported as influenza A(H1N1)pdm09, followed by some influenza A(H3N2) and some influenza B viruses.
• In temperate South America, influenza activity continued to decrease overall. Influenza A(H3N2) viruses predominated among subtyped detections. 
• In the Caribbean and Central American countries, low influenza activity was reported with influenza A(H3N2) predominant.
• In the tropical countries of South America, influenza detections were low and A(H3N2) detections predominated.
• In tropical Africa, influenza activity continued to decrease. Influenza A(H1N1)pdm09 predominated.
• In Southern Asia activity fluctuated at low levels. Influenza A(H3N2) predominated.
• In South-East Asia, influenza virus detections increased. Influenza A(H3N2) predominated.
• In the countries of North America, influenza activity continued to decrease compared to the previous period and influenza positivity was close to levels typically observed at 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 overall in Canada and the United States of America (USA).
• In Europe, overall influenza activity continues to decline with influenza A(H3N2) predominant among the subtyped viruses.
• In Central Asia, no influenza detections were reported.
• In Northern Africa, no influenza detections were reported.
• In East Asia, influenza activity continued to increase driven by increased influenza A(H3N2) detections in the southern provinces of China where influenza-like illness (ILI) activity also increased . Elsewhere, influenza illness indicators and activity remained low. 
• In Western Asia, low numbers of detections of influenza A(H1N1)pdm09, A(H3N2) and B viruses were reported.
• National Influenza Centres (NICs) and other national influenza laboratories from 91 countries, areas or territories reported data to FluNet for the time period from 13 June 2022 to 26 June 2022* (data as of 7/8/2022 3:46:21 AM UTC). The WHO GISRS laboratories tested more than 16 3505 specimens during that time period. 9741 were positive for influenza viruses, of which 9582 (98.37%) were typed as influenza A and 159 (1.63%) as influenza B. Of the sub-typed influenza A viruses, 211 (3.61%) were influenza A(H1N1)pdm09 and 5640 (96.39%) were influenza A(H3N2). Of the characterized B viruses, 46 (100.00%) 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.

• COVID-19 positivity from sentinel surveillance increased over the reporting period. The greatest increases were observed in the African Region of WHO, the European Region of WHO and Region of the Americas of WHO. In the other Regions of WHO positivity was below 25%. Activity from non-sentinel sites continued to increase, with overall positivity around 40%. 
• National Influenza Centres (NICs) and other national influenza laboratories from 101 countries, areas or territories reported data to FluNet for the time period from six WHO regions (African Region: 16; Region of the Americas: 22; Eastern Mediterranean Region: 7; European Region: 43; South-East Asia Region: 6; Western Pacific Region: 7 ) reported to FluNet from sentinel surveillance sites for time period from 13 June 2022 to 26 June 2022* (data as of 7/8/2022 3:46:21 AM UTC). The WHO GISRS laboratories tested more than 11 312 936 sentinel specimens during that time period and 3 756 614 (33.21%) were positive for SARS-CoV-2. Additionally, more than 96 839 979 non-sentinel or undefined reporting source samples were tested in the same period and 21 712 298 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-423