Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 37 (19 September 2025)

Regional Situation: Influenza activity in the Americas remains low. For SARS-CoV-2, there has been an increase in recent epidemiological weeks (EW), reaching a regional positivity rate of 7%. For RSV, regional circulation shows a downward trend. In North America, influenza activity remains at interseasonal levels. In the Caribbean, circulation is decreasing, with a positivity rate of 7.6%. Subtype A(H1N1)pdm09 continues to be predominant. RSV activity remains low and stable in North America, while in the Caribbean it maintains a positivity rate of 6.6% with an upward trend. SARS-CoV-2 activity is increasing in North America, where positivity reached 8%, while in the Caribbean it decreased to 10%. In Central America, influenza activity continues to decline, with a positivity rate of 5.6%. SARS-CoV-2 activity increased this week with a positivity rate of 6.3%, while RSV decreased this EW to a positivity rate of 12.4%. In the Andean subregion, influenza A activity decreased to a positivity rate of 5%. RSV activity slightly decreased this week to 9.6% positivity, while SARS-CoV-2 circulation increased compared to the previous week, reaching a positivity rate of 8.4%. In Brazil and the Southern Cone, influenza activity slightly increased, with a positivity rate of 3.2%. RSV circulation decreased compared to the previous EW, with a positivity rate of 9.7%, while SARS-CoV-2 activity remains at low levels but shows an upward trend, with a positivity rate of 5%. Circulation of other respiratory viruses (ORVs) shows elevated levels and an upward trend at the regional level. The Brazil and Southern Cone subregion stands out with detections of Rhinovirus, Parainfluenza, and Metapneumovirus.