2022-04-17-世界卫生组织-Influenza_Update_N°_417_13页_1mb

报告摘要

Influenza Update N° 417 Summary (18 April 2022)

Core Content

This Influenza Update N° 417 provides an overview of global influenza activity and surveillance data up to 3 April 2022, with special emphasis on the co-circulation of influenza and SARS-CoV-2 viruses during the ongoing COVID-19 pandemic. The data is reported by the Global Influenza Surveillance and Response System (GISRS) and associated surveillance systems, and is integrated with SARS-CoV-2 surveillance data through FluNet.

Main Points and Key Information

Global Influenza Activity

Overall Activity: Influenza activity remained low globally, but increased since February 2022 after a decline in January 2022.
Impact of the Pandemic: The ongoing pandemic has influenced health-seeking behaviors, testing priorities, and capacities in Member States, making the interpretation of current data cautious.
Recommendations: Countries are advised to prepare for the co-circulation of influenza and SARS-CoV-2, enhance integrated surveillance, and step up influenza vaccination campaigns to prevent severe disease and hospitalizations.

Influenza Subtype Distribution

Influenza A: Predominant in most regions, with A(H3N2) being the most common subtype.
Influenza B: Mainly B/Victoria lineage, with a few B/Yamagata detections.
Global Statistics:
- 36,312 specimens tested positive for influenza.
- 96.5% were influenza A, of which 94.5% were A(H3N2).
- 3.5% were influenza B, with 99.9% being B/Victoria lineage.

Regional Influenza Activity

Northern Hemisphere Temperate Zones

North America:
- Influenza activity increased but remained below pre-pandemic levels.
- Predominantly A(H3N2), with some increase in hospitalizations.
- RSV activity remained low.
Europe:
- Influenza activity stabilized, with A(H3N2) predominant.
- Some countries (e.g., Italy, Netherlands) showed elevated positivity rates (above 30%).
- Excess mortality in older populations declined.
Central Asia:
- Only 1 influenza B detection reported in Kyrgyzstan.
Northern Africa:
- Tunisia reported increasing A(H3N2) detections.
Western Asia:
- Low influenza activity, except in Georgia where A(H3N2) increased.
East Asia:
- Influenza activity decreased in China.
- In Mongolia, ILI rate and pneumonia hospitalizations remained elevated, though RSV decreased.
- Other countries in the region reported low activity.

Tropical Zones

Central America, Caribbean, and South America:
- Influenza activity remained low, with A(H3N2) predominant.
- Some countries (e.g., Nicaragua, Bolivia) showed slight increases in activity.
- SARS-CoV-2 activity declined in most countries.
Tropical Africa:
- Togo reported stable influenza activity.
- Middle Africa had no detections.
- Eastern Africa showed a slight decrease in detections, with Mozambique and Madagascar reporting low levels.
- Ethiopia had a slight increase in influenza activity.
Tropical Asia:
- Low influenza activity, with A(H1N1)pdm09 and B viruses detected in India, Pakistan, and Iran.

Southern Hemisphere Temperate Zones

South America:
- Influenza activity decreased in most countries, with A(H3N2) predominant.
- Argentina reported elevated influenza activity.
South Africa:
- Influenza activity remained below seasonal thresholds.
- RSV detection rates increased in children under 5.
Oceania:
- Very few influenza detections.
- Elevated ILI in New Caledonia, Fiji, French Polynesia, and Kiribati.

SARS-CoV-2 Surveillance

SARS-CoV-2 percent positivity from sentinel surveillance was around 10% in all WHO regions.
South-East Asia showed an increase, while Eastern Mediterranean had a slight uptick.
Non-sentinel sites also reported a decreasing trend in SARS-CoV-2 positivity.
Only a limited number of countries report both influenza and SARS-CoV-2 data consistently to FluNet.

Data Sources and Surveillance

FluNet and GISRS provide the primary data sources.
FluID and WHO Regional Offices also contribute to the surveillance.
The WHO encourages integrated influenza and SARS-CoV-2 surveillance, especially for countries with access to multiplex reagent kits.
Detailed reports are available from regional offices, including:
- Region of the Americas: www.paho.org/influenzareports
- Eastern Mediterranean Region: http://www.emro.who.int/health-topics/influenza/situation-update.html
- European Region: www.flunewseurope.org/
- Western Pacific Region: https://www.who.int/westernpacific/emergencies/surveillance/seasonal-influenza

Additional Information

Integrated Surveillance: The WHO recommends enhancing integrated surveillance for influenza and SARS-CoV-2.
Vaccination Campaigns: Countries are encouraged to increase influenza vaccination to prevent severe outcomes.
Differential Diagnosis: Clinicians should consider influenza in differential diagnosis, especially for high-risk groups.
Data Completeness: Data completeness may vary due to differences in availability and quality of information.