The Pan American Health Organization (PAHO) is urging countries across the Americas to stay on high alert as seasonal influenza and respiratory syncytial virus (RSV) circulate at the same time—an overlap that could strain hospitals and clinics through the rest of the Northern Hemisphere’s winter.
In an epidemiological alert issued January 10, PAHO updated a December advisory that had cautioned countries to prepare for an earlier or more intense respiratory season than usual. Health officials now say those concerns are materializing, with influenza activity climbing steadily since October 2025 and RSV infections also on the rise.
Globally, influenza A(H3N2) is the dominant strain this season, with early and sustained activity already reported in several Northern Hemisphere countries. RSV, a virus that can cause severe illness in infants, older adults, and people with underlying conditions, is showing a gradual but consistent increase as well.
Across the Americas, influenza test positivity remains above 10 percent in the Northern Hemisphere. North and Central America are seeing sustained increases, while levels in the Caribbean are approaching 20 percent, again largely driven by A(H3N2).
Data from countries including the United States, Canada, the United Kingdom, and Spain point to an early and fast-moving flu season. Health systems in those countries have reported a rise in outpatient visits—especially among children—and increasing hospitalizations, particularly among older adults.
PAHO notes that while the overall severity of the season so far appears similar to previous years and no excess mortality has been observed, some countries are recording higher-than-usual levels of influenza detection and visits for influenza-like illness. The added pressure of rising RSV circulation could further challenge health services if trends continue.
“The simultaneous circulation of influenza and RSV is a significant challenge,” said Dr. Marc Rondy, PAHO’s Regional Adviser in Epidemiology of Epidemic- and Pandemic-Prone Diseases. “It requires us to prioritize vaccination, which protects against severe cases that may require hospitalization, and to maintain close surveillance so we can act quickly and avoid hospital overcrowding.”
PAHO highlighted interim studies showing that current influenza vaccines remain effective at preventing severe illness, with an estimated effectiveness of 30–40 percent in adults and about 75 percent in children. The organization is calling on countries to boost vaccination coverage, particularly among priority groups such as young children, pregnant people, older adults, and those living with chronic conditions.
To manage the dual threat, PAHO recommends that countries strengthen integrated surveillance for influenza, RSV, COVID-19, and other respiratory viruses, and report weekly data to global monitoring systems. Health authorities are also advised to review and adjust hospital response plans in anticipation of possible simultaneous surges.
Additional recommendations include prioritizing influenza and COVID-19 vaccinations for high-risk groups, implementing RSV prevention strategies—such as maternal vaccination and long-acting monoclonal antibodies for newborns and infants—and reinforcing public health messaging.
For the public, PAHO says basic prevention still goes a long way: getting vaccinated, washing hands frequently, covering coughs and sneezes, wearing a mask indoors when sick, staying home with fever or respiratory symptoms, and seeking medical care promptly if symptoms become severe. These measures, officials stress, are especially important to protect young children and older adults as respiratory virus activity continues to climb.
