Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 36 (12 September 2025)

Regional Situation: Influenza activity in the Americas remains low. SARS-CoV-2 shows an increase in recent epidemiological weeks (EW). RSV circulation at the regional level 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%. Subtype A(H1N1)pdm09 continues to be the predominant strain. RSV activity remains low and stable in North America, while in the Caribbean it maintains a positivity rate of 4.9%. SARS-CoV-2 activity is increasing in North America and the Caribbean, where positivity reached 14.4%, respectively. In Central America, influenza activity continues to decline, with a positivity rate of 5.6%. SARS-CoV-2 activity remains steady this week, with a positivity rate of 5.1%, while RSV maintains a positivity rate of 15.5% in the current EW. In the Andean subregion, influenza A activity remains stable compared to the previous EW, with a positivity rate of 5.4%. RSV activity increases to a positivity rate of 10.1%, while SARS-CoV-2 circulation shows a slight decrease compared to the previous week, with a positivity rate of 5.9%. In Brazil and the Southern Cone, influenza activity continues to decline, with a positivity rate of 2.7%. RSV circulation decreases compared to the previous EW, with a positivity rate of 10.9%, while SARS-CoV-2 activity remains at low levels but shows an upward trend. Circulation of other respiratory viruses (ORVs) remains elevated and shows an increasing trend at the regional level. The Brazil and Southern Cone subregion stands out for the detection of Rhinovirus, Parainfluenza, and Metapneumovirus.