Health authorities in the Americas are on high alert due to a concerning development: the simultaneous circulation of seasonal influenza and respiratory syncytial virus (RSV). This dual threat could put additional strain on hospitals and clinics throughout the winter season in the Northern Hemisphere, as warned by the Pan American Health Organization (PAHO).
The situation is particularly critical as influenza activity has been steadily rising since October 2025, with A(H3N2) predominating. Early signs of seasonal activity have been observed in several Northern Hemisphere countries, while RSV circulation is also showing a gradual upward trend. In the Americas, influenza positivity remains above 10% in the Northern Hemisphere, with sustained increases in North and Central America and levels approaching 20% in the Caribbean, where A(H3N2) predominates.
The impact is already being felt in some countries, with increased outpatient visits, particularly among children, and rising hospitalizations, especially among older adults. While these patterns align with expected seasonal dynamics, some countries are experiencing activity levels that exceed those of recent seasons. This is where the concern lies: the gradual increase in RSV circulation could further strain health systems, making close and continuous monitoring essential to adjust health service response plans.
Dr. Marc Rondy, PAHO Regional Adviser in Epidemiology of Epidemic- and Pandemic-Prone Diseases, emphasizes the importance of vaccination. Current influenza vaccines are effective at preventing hospitalizations (30–40% effectiveness in adults and 75% in children). PAHO calls on countries to achieve high vaccination coverage, especially among priority groups such as children, pregnant people, older adults, and those with chronic conditions.
To combat this dual threat, PAHO recommends that countries in the region:
- Strengthen integrated surveillance of influenza, RSV, SARS-CoV-2, and other respiratory viruses, reporting weekly data to FluNET and FluID to support regional and global monitoring.
- Prepare and adjust health service response plans to address possible simultaneous increases in influenza and RSV cases and hospitalizations.
- Prioritize influenza and COVID-19 vaccination for at-risk groups, including older adults, young children, pregnant people, individuals with chronic conditions, and healthcare workers.
- Implement RSV prevention strategies, including maternal vaccination and long-acting monoclonal antibodies for newborns and infants, in line with PAHO/WHO recommendations.
- Strengthen risk communication, promoting key preventive practices.
PAHO reminds the public that vaccination against influenza, frequent handwashing, covering the mouth when coughing or sneezing, wearing masks indoors if symptomatic, staying home when experiencing fever or respiratory symptoms, and seeking prompt medical care for severe symptoms are simple and effective ways to protect themselves and their families, especially young children and older adults.
