The Pan American Health Organization (PAHO) has urged countries across the Americas to remain vigilant and strengthen health system preparedness in response to the simultaneous circulation of seasonal influenza and respiratory syncytial virus (RSV). This situation could place additional pressure on hospitals and clinics for the remainder of the winter season in the Northern Hemisphere.
The epidemiological alert, issued yesterday, updates an advisory released on December 4, 2025, which warned of the possibility of an earlier or more intense respiratory season than usual.
Globally, influenza activity has been steadily increasing since October 2025, with A(H3N2) predominating and early signs of seasonal activity observed in several Northern Hemisphere countries. At the same time, RSV circulation is 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.
Analysis of selected countries (the United States, Canada, the United Kingdom, and Spain) indicates an early and rapid start to the influenza season in the Northern Hemisphere, with increased outpatient visits—particularly among children—and rising hospitalizations, especially among older adults.
While these patterns align with expected seasonal dynamics and overall severity remains comparable to previous seasons, with no excess mortality observed to date, some countries are experiencing activity levels—measured by influenza detection and outpatient visits for influenza-like illness—that exceed those of recent seasons.
In this context, the gradual increase in RSV circulation could further strain health systems, making close and continuous monitoring essential to adjust health service response plans.
“The simultaneous circulation of influenza and RSV is a significant challenge that requires us to prioritize vaccination—which protects against severe cases that may require hospitalization—and maintain close surveillance, enabling timely action to prevent larger outbreaks and avoid hospital overcrowding,” said Dr. Marc Rondy, PAHO Regional Adviser in Epidemiology of Epidemic- and Pandemic-Prone Diseases.
PAHO emphasizes that interim studies show current influenza vaccines are effective at preventing hospitalizations (30–40% effectiveness in adults and 75% in children), and calls on countries to achieve high vaccination coverage, especially among priority groups such as children, pregnant people, older adults, and those with chronic conditions.
In light of this situation, 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.
