Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 35 (5 September 2025)

Regional Situation: Influenza activity in the Americas remains low. SARS-CoV-2 activity has shown an increase in recent epidemiological weeks (EW). At the regional level, RSV 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 8.5%. Subtype A(H1N1)pdm09 continues to be the predominant strain. RSV activity remains low and stable in North America, while in the Caribbean it is decreasing, reaching a positivity rate of 4.9% in the latest EW. SARS-CoV-2 activity is increasing in North America and the Caribbean, where positivity rates reached 6.6% and 19.8%, respectively. In Central America, influenza activity continues to decline, with a positivity rate of 6.5%. SARS-CoV-2 activity remains stable this week, with a positivity rate of 5.7%, while RSV decreased this EW to a positivity rate of 14.9%. In the Andean subregion, influenza A activity continues its downward trend, with a positivity rate of 5.4%. RSV activity decreased to a positivity rate of 8.8%, while SARS-CoV-2 circulation increased slightly compared to the previous week, reaching a positivity rate of 6.4%. In Brazil and the Southern Cone, influenza activity continues to decline, with a positivity rate of 2.8%. RSV circulation decreased compared to the previous EW, with a positivity rate of 11.7%, while SARS-CoV-2 activity remains at low levels but shows an upward trend. Circulation of other respiratory viruses (ORVs) is elevated and shows an upward trend in most subregions. The Brazil and Southern Cone subregion stands out with detections of Rhinovirus, Parainfluenza, and Metapneumovirus.