Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 39 ( 3 October 2025)

Regional Situation: Influenza activity in the Americas remains low, with an upward trend beginning this week. At the regional level, RSV circulation shows a downward trend, while SARS-CoV-2 has increased in recent epidemiological weeks (EW), reaching a positivity rate of 8.3%. In North America, influenza activity remains at interseasonal levels. RSV circulation remains low and stable, while SARS-CoV-2 is increasing, with a positivity rate of 10%. In the Caribbean, influenza circulation is decreasing, with a positivity rate of 6%, predominantly subtype A(H1N1)pdm09. RSV activity is increasing this EW, reaching a positivity rate of 6.2%, while SARS-CoV-2 circulation is declining to 7%. In Central America, influenza activity is slightly increasing, with a positivity rate of 6.6%. SARS-CoV-2 shows a decrease this week (3.4% positivity), while RSV also declines, with a positivity rate of 13.3%. In the Andean subregion, influenza A activity is decreasing to 4.8% positivity. RSV shows a reduction this week (6.9% positivity), while SARS-CoV-2 decreases compared to the previous week, reaching a positivity rate of 7.4%. In Brazil and the Southern Cone, influenza activity shows a slight increase (4.3% positivity). RSV circulation decreases compared to the previous EW, with a positivity rate of 5.7%, while SARS-CoV-2 remains at low levels, though with an upward trend (5.9% positivity). The circulation of other respiratory viruses (ORVs) remains elevated and continues to trend upward at the regional level.