Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 9 (13 March 2026)

Regional Situation: Influenza activity in the Americas decreased this week (14.6%) compared to the previous epidemiological week (EW), following five weeks of relatively stable activity with positivity levels around 16%. This extended period of sustained activity was associated with increased circulation of influenza B in the Northern Hemisphere, which appears to have prolonged the season. Overall, in the last four weeks, co-circulation of influenza A and B has been observed in North America. Influenza A(H3N2) predominated in the Caribbean, the Andean Region, Brazil, and the Southern Cone, while influenza A(H1N1)pdm09 was more prevalent in Central America. RSV circulation continued its upward trend, reaching a positivity of 2.2%, while SARS-CoV-2 circulation remained stable at 4.9%, driven by activity in North America, Brazil, and the Southern Cone. Circulation of other respiratory viruses (ORV) also increased, reaching a regional positivity of 2.6%, mainly driven by coronaviruses.