2022-08-21-世界卫生组织-Influenza_Update_N°_426_11页_1mb

Influenza Update Summary (8 August 2022)

Overview

• Current influenza surveillance data should be interpreted cautiously due to the impact of the ongoing COVID-19 pandemic on health-seeking behaviours, surveillance systems, and testing priorities/capacities.
• Implementation of various COVID-19 mitigation measures has likely reduced influenza transmission.
• Countries are advised to monitor the co-circulation of influenza and SARS-CoV-2, enhance integrated surveillance, step up influenza vaccination campaigns, and consider influenza in clinical differential diagnoses, especially in high-risk groups, following national guidance.

Global Influenza Activity

• Global influenza activity has been steadily decreasing since peaking in March 2022, except in Southeast Asia where activity increased.
• Activity was generally at inter-seasonal levels in temperate zones of the northern and southern hemispheres.
• The Southern Hemisphere overall showed further reduced activity in temperate zones.
• Co-circulation continued, with influenza A(H3N2) being predominant globally (makes up the majority of A viruses typed/subtyped), followed by influenza A(H1N1)pdm09, and B viruses (Victoria lineage).

Regional Details

• Temperate Southern Hemisphere (e.g., Australia/NZ, South America, Caribbean/Central America):
  • Activity declined further in most areas.
  • Influenza A(H3N2) dominated activity reported.
• Tropical Regions (e.g., South/East/West/Central/Africa, South/East/Southern Asia):
  • Activity decreased overall, with A(H3N2) predominating.
  • Some areas saw increases (e.g., India, South East Asia) or fluctuating COVID-19 rates, SARI levels driven by other viruses.
• Northern Hemisphere Temperate Regions (North America, Europe):
  • Activity remained low and seasonal rates typically fluctuate at this time, with A(H3N2) dominating.
• Asia (East/West/Southern): Activity low in some parts (e.g., northern China, Central Asia, North Africa, Oman, Northern Africa). Peak reported in southern China for A(H3N2). Moderate activity in South/East Asia. No detections in Central Asia, Northern Africa.

SARS-CoV-2 Context

• Integrated surveillance for both influenza and SARS-CoV-2 is encouraged.
• SARS-CoV-2 positivity rates from sentinel surveillance were decreasing, varying by region, alongside overall activity related to other respiratory viruses.

Data Source and Notes

• Data compiled from the Global Influenza Surveillance and Response System (GISRS) via FluNet, updated daily between July 25 - August 7, 2022.
• A limited number of countries consistently report both influenza and SARS-CoV-2 data to FluNet, affecting comprehensive regional trends.