全球呼吸道病毒活动：每周更新N°561

GLOBAL INFLUENZA SURVEILLANCE AND RESPONSE SYSTEM (GISRS) Co-circulationInfluenzaSARS-CoV-2 SUMMARY End-of year holiday season may affect the surveillance testing and reporting practices in one or more regions. Globally, influenza activity was elevated withpositivity just under 20% in week 2 2026. SARS-CoV-2 activity remained stable and low overall. Influenza predominated and positivity was around 20% inthe northern hemisphere temperate and sub-tropical areas, and just under 20% in the tropical areas. In the southern hemisphere temperate and subtropical qInfluenza Globally, influenza detections appeared to decline; however, this could be an artifact due to delayed reporting in some regions. Influenza A viruses In the northern hemisphere, influenza percent positivity was elevated (>10%) in countries in North America and Western and Middle Africa. Percentpositivity was over 30% in countries in Central America and the Caribbean, Tropical South America, Northern Africa, Europe, and Western, Southern, In the southern hemisphere, influenza activity remained low overall although elevated positivity (>10%) was reported in a single countries inTemperate South America, Eastern Africa, South-East Asia and Oceania; percent positivity was over 30% in a single country in Tropical South In the zones with elevated positivity, influenza A(H3N2) was predominant in all zones except Tropical South America where there was codominance ofinfluenza A(H1N1)pdm09 and A(H3N2). [Figures 5 and 6] qSARS-CoV-2 Globally, SARS-CoV-2 positivity remained stable and low, with single countries reporting elevated positivity (>10%) in South West and EasternEurope and two countries in Temperate South America. A small increase in activity was reported in a single country in Temperate South America. qRespiratory Syncytial Virus (RSV)RSV activity was stable and low overall although elevated percent positivity (>10%) was reported in few countries in Central America and the Caribbean, South West and Northern Europe, and Western Asia. Increases in activity compared to the previous reporting period were reported in afew countries in South West and Northern Europe. [Figures 9 and 10] RSV and influenza activity were both elevated in single countries in Central qSeverity assessment The severity assessments here are reported from countries, areas and territories. Assessments for transmissibility can be reported based on syndromicparameters and/or influenza-specific parameters. In northern hemisphere temperate and subtropical areas, influenza-specific transmissibility wasreported as below seasonal threshold (1) and moderate (1); transmissibility using syndromic data was reported as below seasonal threshold (9), low (12) and moderate (12). In tropical areas, influenza-specific transmissibility was reported as below seasonal threshold in a single country. [Figures 11 Co-circulation of influenza and SARS-CoV-2 1b) Weekly numbers of influenza andSARS-CoV-2 virus specimens tested and Influenza SARS-CoV-2 8) Change in proportions of specimens that tested Respiratory syncytial virus Severity assessment Additional information Data and methods The data presented in this report originates from virologic surveillance conducted by countries, areas, and territories (CATs) and submitted to WHO FluNet through participation orcollaboration with the Global Influenza Surveillance and Response System (GISRS). These CATs employ diverse methodologies to monitor respiratory virus activity, which may resultin variations between this report and other surveillance summaries published elsewhere. To assess trends, the proportion of specimens tested positive for influenza or SARS-CoV-2 was smoothed over a 3-weeks period. This analysis includes only countries that tested 10 ormore specimens in at least two of the three weeks. Weekly changes in the smoothed positivity rate for each virus were calculated as absolute differences from the previous week. These The influenza transmission zones map is based on data aggregated over a 3-weeks period, moving backward from the current week until a minimum threshold of 100 tested samples isreached within each influenza transmission zone. Pie charts are displayed on the map only if the total percent positivity in a influenza transmission zones map is 20% or higher. Alltrend analyses are based on ISO 8601 calendar week numbering. Activity summaries are organized by geographical groupings of CATs. These groupings are intended solely for geographic reference and do not imply uniformity in respiratory virustransmission patterns within each group. It is important to note that specimens tested for influenza, SARS-CoV-2, and RSV may not originate from the same sample sources within Severity assessments: The severity assessments here are reported from countries, areas and territories.WHO’s Pandemic influenza severity assessment (PISA): a WHO guide to assess the severityof influenza in seasonal epidemics and pandemics, 2nd ed ou