2022-03-06-世界卫生组织-Influenza_Update_N°_414_12页_1mb

报告摘要

Influenza Update N° 414 Summary (7 March 2022)

Core Content

This document provides an overview of global influenza activity and surveillance data up to 20 February 2022, highlighting the impact of the ongoing COVID-19 pandemic on influenza trends and the importance of integrated surveillance for both influenza and SARS-CoV-2 viruses.

Key Findings

Global Influenza Activity

Influenza activity globally remained low and decreased during the period after a peak at the end of 2021.
The pandemic has influenced health-seeking behaviors, testing priorities, and capacities, making interpretation of data cautious.
Countries are advised to prepare for co-circulation of influenza and SARS-CoV-2 and to enhance integrated surveillance.
Influenza vaccination campaigns are encouraged to prevent severe disease and hospitalizations.

Influenza Virus Types

Influenza A (H3N2) was the predominant strain globally.
Influenza B (Victoria lineage) was also widely detected.
Influenza A (H1N1)pdm09 was less common but still reported in some regions.

SARS-CoV-2 Data

SARS-CoV-2 percent positivity from sentinel surveillance decreased across all WHO regions.
Positivity rate was above 50% in the Eastern Mediterranean Region, and between 20% and 30% in other regions, except the African Region where it remained under 10%.
Non-sentinel sites also showed a decreasing trend in SARS-CoV-2 positivity.

Regional Overview

Northern Hemisphere (Temperate Zones)

North America: Influenza activity remained low, with A(H3N2) predominant. RSV activity decreased further. Influenza hospitalizations increased slightly.
Europe: Influenza activity remained stable at low levels, with A(H3N2) predominant. RSV activity was minimal. Mortality rates remained elevated, especially among the elderly.
East Asia: Influenza activity decreased in China, with B/Victoria lineage predominant. Mongolia reported elevated ILI and hospitalization rates, likely due to the impact of the pandemic.
Northern Africa: Influenza detections decreased slightly, with A(H3N2) predominant in most areas.
Western Asia: Low influenza activity was reported, with A(H3N2) and B viruses detected.
Caribbean and Central America: Influenza activity remained low, with A(H3N2) predominant. SARI cases in Costa Rica showed a high proportion of SARS-CoV-2 positivity.
Tropical South America: Influenza activity decreased and returned to normal levels for the season.
Tropical Africa: Influenza activity was reported in Eastern and Middle Africa, with A(H3N2) and B viruses detected. Western Africa had sporadic detections.
Southern Asia: Influenza activity decreased, with A(H3N2) predominant. Pakistan saw an increase in A(H1N1)pdm09 detections.
South-East Asia: Influenza A(H3N2) and some B viruses were reported. The Philippines and Timor-Leste saw decreased influenza A activity.

Southern Hemisphere (Temperate Zones)

Influenza activity remained low, as expected for this time of year.
Temperate South America: Argentina reported increased influenza activity with high positivity, while Chile saw a decrease. Paraguay had baseline positivity.
Oceania: Very few influenza detections were reported, except in French Polynesia.
South Africa: Influenza transmission and impact were below seasonal thresholds, with only one influenza B (Victoria lineage) case reported outside routine surveillance.

Recommendations

Countries are encouraged to enhance integrated surveillance for influenza and SARS-CoV-2.
Influenza vaccination campaigns should be stepped up to prevent severe outcomes.
Clinicians should consider influenza in differential diagnoses, especially for high-risk groups.
Timely and consistent reporting to FluNet is important for accurate surveillance and response.

Data Sources

FluNet: Monitors influenza activity globally and includes SARS-CoV-2 testing data from sentinel systems.
FluID: Provides epidemiological data from national focal points.
WHO Regional Offices: Supply influenza reports and updates.
GISRS: Conducts global influenza surveillance and testing.