Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 38 (26 September 2025)

Regional Situation:  Influenza activity in the Americas remains low. At the regional level, RSV circulation shows a downward trend, while SARS-CoV-2 has increased in recent epidemiological weeks (EW), reaching a regional positivity of 7.7%. In North America, influenza activity remains at interseasonal levels. RSV circulation remains low and stable, while SARS-CoV-2 shows an increase, with a positivity of 9%. In the Caribbean, influenza circulation is decreasing, with a positivity of 6%, predominantly driven by subtype A(H1N1)pdm09. RSV activity is also declining, reaching a positivity of 3.9%, as is SARS-CoV-2, which has dropped to 9.2%. In Central America, influenza activity has slightly increased, with a positivity of 6.4%. SARS-CoV-2 shows a decrease this week (5.2% positivity), while RSV also declined, with a positivity of 14%. In the Andean subregion, influenza A activity decreased to 5% positivity. RSV shows a slight reduction this week (8.7% positivity), while SARS-CoV-2 increased compared to the previous week, reaching a positivity of 9.8%. In Brazil and the Southern Cone, influenza activity shows a slight increase (3.6% positivity). RSV circulation decreased compared to the previous EW, with a positivity of 7.2%, while SARS-CoV-2 remains at low levels but with an upward trend (5.6% positivity). The circulation of other respiratory viruses (ORVs) remains elevated and continues to rise at the regional level, with notable detections of Rhinovirus, Parainfluenza, and Metapneumovirus in Brazil and the Southern Cone subregion.