2021-08-29-世界卫生组织-Influenza_Update_N°_401_11页_1mb

报告摘要

Influenza Update N° 401 Summary

Core Content

This document provides an influenza surveillance update for the period from 02 August 2021 to 15 August 2021, with data as of 27 August 2021. It includes information on both influenza and SARS-CoV-2 virus detections from sentinel and non-sentinel surveillance systems, reported to FluNet by the WHO Global Influenza Surveillance and Response System (GISRS) and associated national influenza laboratories.

Main Points

General Context

The ongoing COVID-19 pandemic has affected health-seeking behaviors, staffing and routines in sentinel sites, and testing priorities and capacities in Member States.
Hygiene and physical distancing measures have likely contributed to the reduction of influenza virus transmission.

Global Influenza Activity

Influenza activity globally remained at lower levels than expected for this time of the year.
Influenza A accounted for the majority of detections, with A(H3N2) being the dominant subtype.
Influenza B was also detected, all belonging to the B-Victoria lineage.

Regional Influenza Activity

Southern Hemisphere (Temperate Zones)

Interseasonal levels of influenza activity were observed.
Oceania: ILI and other indicators remained low, though ORVs were detected at usual levels.
Australia: Parainfluenza and human metapneumovirus activity was higher than historical levels in Western Australia.
New Zealand: SARI rates were below seasonal thresholds, with rhinovirus, parainfluenza, and RSV being the most common viruses.
South Africa: Influenza B detections were reported, though activity remained interseasonal. RSV activity was also reported but below seasonal levels.
South America (Temperate): No influenza virus detections were reported, while RSV activity remained elevated in Argentina.

Tropical Zones

Central America and Caribbean: Sporadic influenza A and B detections were reported from Mexico. RSV activity was low.
Tropical South America: No influenza virus detections were reported. RSV activity increased in Peru.
Tropical Africa:
- Western Africa: Influenza A(H1N1)pdm09 was detected in Côte d'Ivoire.
- Middle Africa: No influenza detections were reported despite ongoing testing in Chad and Democratic Republic of Congo.
- Eastern Africa: Predominantly influenza A(H3N2) was reported from Ethiopia.

Northern Hemisphere (Temperate Zones)

Overall influenza activity remained below baseline.
North America: Influenza indicators were very low, with ILI activity increasing in children under 5. RSV and parainfluenza activity increased in parts of the USA.
Europe: Interseasonal levels of influenza activity, with few detections in Netherlands, Sweden, and UK. ORVs continued to be reported in some countries. Mortality estimates were at expected levels.
Central Asia: No influenza detections were reported.
Northern Africa: No reports received, but Egypt reported A(H3N2) and B detections in earlier weeks.
Western Asia: Low influenza activity and ILI rates, with Qatar reporting increased A(H3N2).
East Asia: Low influenza activity, with Hong Kong SAR showing lower ILI consultations than expected. Influenza B/Victoria was detected in southern China at similar levels to the previous period but lower than previous years. Hospitalizations due to pneumonia continued to increase in Mongolia.

SARS-CoV-2 Sentinel Surveillance

SARS-CoV-2 data are included from countries reporting sentinel specimens.
Global SARS-CoV-2 positivity from sentinel surveillance was 38%.
Regional activity:
- Americas: Elevated positivity in American, Eastern Mediterranean, European, and South-East Asia Regions, with a decline in the African Region.
- Western Pacific Region: Low SARS-CoV-2 activity from sentinel surveillance.

Key Information

Testing and reporting: 81 countries, areas, or territories reported influenza data, and 35 reported SARS-CoV-2 data.
GISRS laboratories tested over 215,281 specimens, with 1,424 positive for influenza.
SARS-CoV-2 testing: Over 2 million non-sentinel specimens were tested, with 427,590 positive.
Influenza A(H3N2) was the most common subtype globally, with 93.8% of all A viruses.
Influenza B was reported in all regions, with 100% belonging to the B-Victoria lineage.

Data Sources and Limitations

Data is collected from FluNet, FluID, and WHO Regional Offices.
Completeness of data may vary due to availability and quality.
Trends in percent positivity for SARS-CoV-2 do not reflect the entire regional situation, as data is limited and not consistent across all countries.