The Pan American Health Organization (PAHO) has urged countries across the Americas to remain vigilant and strengthen health system preparedness due to the simultaneous circulation of seasonal influenza and respiratory syncytial virus (RSV). This dual circulation could place additional pressure on hospitals and clinics for the remainder of the Northern Hemisphere winter season. The alert updates a previous advisory from December 2025, which warned of a potentially earlier or more intense respiratory season than usual.
Globally, influenza activity has been rising steadily since October 2025, with the A(H3N2) strain predominating and early seasonal activity observed in several Northern Hemisphere countries. At the same time, RSV circulation is gradually increasing. 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.
Data from countries including the United States, Canada, the United Kingdom, and Spain show an early and rapid start to the influenza season, with increased outpatient visits—especially among children—and rising hospitalizations, particularly among older adults. While overall severity remains comparable to previous seasons and no excess mortality has been observed, some countries are seeing higher activity levels measured by influenza detection and outpatient visits for influenza-like illness.
The simultaneous rise of RSV circulation could further strain health systems, highlighting the need for close and continuous monitoring to adjust health service response plans. Dr. Marc Rondy, PAHO Regional Adviser in Epidemiology of Epidemic- and Pandemic-Prone Diseases, emphasized that prioritizing vaccination and maintaining close surveillance are critical to preventing larger outbreaks and avoiding hospital overcrowding.
PAHO notes that current influenza vaccines remain effective at preventing hospitalizations, with 30–40% effectiveness in adults and 75% in children, and urges countries to ensure high vaccination coverage, particularly among children, pregnant people, older adults, and individuals with chronic conditions.
In response to this situation, PAHO recommends that countries strengthen integrated surveillance of influenza, RSV, SARS-CoV-2, and other respiratory viruses, reporting weekly data to FluNET and FluID. Health service response plans should be prepared and adjusted to address potential simultaneous increases in influenza and RSV cases and hospitalizations. Vaccination efforts should prioritize at-risk groups, while RSV prevention strategies, including maternal vaccination and long-acting monoclonal antibodies for infants, should be implemented according to PAHO/WHO guidance. Risk communication should also be strengthened to promote 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 illness are simple and effective ways to protect individuals and families, especially young children and older adults.
