全球呼吸道病毒活动：每周更新N°571

GLOBAL INFLUENZA SURVEILLANCE AND RESPONSE SYSTEM (GISRS) Co-circulationInfluenzaSARS-CoV-2RSVSeverity assessment SUMMARY Globally, influenza positivity was below 10% in week 12 2026. SARS-CoV-2 activity remained low overall. Influenza predominated and positivity wasbelow 10% in the northern hemisphere temperate and subtropical areas and in tropical areas. In the southern hemisphere temperate and subtropical areas,influenza and SARS-CoV-2 positivity were both low. [Figures 1a, 1b, 1c and 1d] Globally, RSV positivity remained stable and low. qInfluenza Globally, influenza detections continued to decline in week 12 and influenza B viruses were predominant among influenza detections. [Figure 2] In the northern hemisphere, influenza percent positivity was elevated (>10%) in a single country in North America and in countries in South WestEurope, Southern, Eastern and South-East Asia. Percent positivity was over 30% in countries in Central America and the Caribbean, and in a singlecountry in Western Africa and Northern and Eastern Europe. Increases in activity were observed in a few countries in Central America and theCaribbean and in single countries in Western and Eastern Africa. [Figures 3 and 4] In the southern hemisphere, influenza activity remained low overall although elevated positivity (>10%) was reported in single countries in TemperateSouth America, Southern Africa and South-East Asia. Percent positivity was over 30% in one country in Tropical South America. No countriesreported increase in activity in week 12. [Figures 3 and 4] In the zones with elevated positivity, influenza A(H3N2) was predominant in Central America and the Caribbean, Tropical and Temperate SouthAmerica, Eastern Europe and Southern Asia.Influenza A(H1N1)pdm09 was predominant in Southern Africa and Northern Europe.InfluenzaA(H1N1)pdm09 and A(H3N2) were codominant in South West Europe. Influenza B was dominant in North America, Western Africa, Eastern andSouth-East Asia. [Figures 5 and 6] qSARS-CoV-2Globally, SARS-CoV-2 positivity remained stable and low, with a single country reporting elevated activity (>10%) in Oceania. [Figures 7 and 8] qRespiratory Syncytial Virus (RSV)Globally, RSV positivity remained stable and low, with a few countries reporting elevated positivity (>10%) in Europe and single countries in Tropical South America and Western Asia. Percent positivity was over 30% in single countries in Eastern and Northern Africa, and Central Asia. Smallincreases in activity were reported in a few countries in Eastern Europe, and single countries in Eastern Africa and South West Europe. [Figures 9 and10] RSV and influenza activity were both elevated in a few countries in Tropical South America and Europe. qSeverity assessmentThe severity assessments here are reported from countries, areas and territories. Assessments for transmissibility can be reported based on syndromic parameters and/or influenza-specific parameters. In the northern hemisphere temperate and subtropical areas, influenza-specific transmissibility wasreported as below seasonal threshold (18), low (13) and moderate (3); transmissibility using syndromic data was reported as below seasonal threshold(24) and low (3). Influenza-specific transmissibility was reported as below seasonal threshold in a single country in the southern hemisphere temperateand subtropical areas. In the tropical areas, influenza-specific transmissibility was reported as below seasonal threshold (2), and transmissibility usingsyndromic data was reported as below seasonal threshold in a single country. [Figures 11 and 12] Co-circulation of influenza and SARS-CoV-2 1c) Weekly numbers of influenza andSARS-CoV-2 virus specimens tested andpercent positivity in tropical areas 1d) Weekly numbers of influenza andSARS-CoV-2 virus specimens tested andpercent positivity in southern hemispheretemperate and subtropical areas 1b) Weekly numbers of influenza andSARS-CoV-2 virus specimens tested andpercent positivity in northern hemispheretemperate and subtropical areas Influenza 3) Proportions of specimens that tested positive forinfluenza (year-week:2026-12) 4) Change in proportions of specimens that testedpositive for influenza (year-week:2026-12) 6) Weekly distribution of influenza virus types andsubtypes by geographic zone (last 12 months) 5) Proportions of influenza virus types and subtypes byinfluenza transmission zones (year-week:2026-12) SARS-CoV-2 7) Proportions of specimens that tested positive forSARS-CoV-2 (year-week:2026-12) 8) Change in proportions of specimens that testedpositive for SARS-CoV-2 (year-week:2026-12) Respiratory syncytial virus 9) Proportions of specimens that tested positive for RSV(year-week:2026-12) 10) Change in proportions of specimens that testedpositive for RSV (year-week:2026-12) Severity assessment 12) Syndromic transmissibility (year-week:2026-12) 11) Influenza specific transmissibility (year-week:2026-12) 13) Number of countries, areas or