PAHO warns of dual influenza and RSV circulation across the Americas

The Pan American Health Organization issued an epidemiological alert from Washington, D.C., on January 10, 2026, urging countries across the Americas to strengthen surveillance, vaccination and health system preparedness in response to simultaneous circulation of seasonal influenza and respiratory syncytial virus. The agency warned that concurrent activity of both viruses could add pressure to hospitals and clinics for the remainder of the Northern Hemisphere winter season.

PAHO said influenza activity had increased regionally since late 2025, with influenza A(H3N2) the predominant virus in many reporting areas and A(H1N1)pdm09 identified as the leading strain in the Andean subregion. Overall influenza test positivity in the Americas’ Northern Hemisphere remained above 10 percent, with rates approaching 20 percent in parts of the Caribbean and Central America. Countries named by PAHO as reporting high levels of influenza circulation included Barbados, Canada, Ecuador, Guatemala, Nicaragua, Panama, Paraguay and the United States.

While PAHO described current RSV circulation as lower than influenza in many places, the agency cautioned that RSV activity could rise gradually and compound health care demand. PAHO stressed that overlapping outbreaks of influenza and RSV were possible during the 2025-26 season and that even a modest increase in RSV cases would add to inpatient and pediatric burdens already elevated by influenza.

The alert focused on measures to prevent health system overcrowding, calling on national authorities to adapt organizational and surge plans, scale up laboratory and clinical surveillance, and prioritize vaccination programs. Dr. Marc Rondy, PAHO Regional Adviser in Epidemiology of Epidemic- and Pandemic-Prone Diseases, underscored vaccination and surveillance "to prevent larger outbreaks and avoid hospital overcrowding."

Public health guidance issued with the alert reiterated standard precautions: receive influenza vaccination, practice frequent handwashing, cover the mouth when coughing or sneezing, wear a mask indoors if symptomatic, stay home when experiencing fever or respiratory symptoms, and seek prompt medical care for severe illness—particularly for young children and older adults. PAHO and WHO also advised international travelers to obtain influenza vaccination before visiting areas with active circulation.

Vaccine access remained robust in the United States, with most clinics and pharmacies offering seasonal flu shots as of January 10. Scientific context for vaccine protection was provided by a University of Pennsylvania study dated January 6, 2026, which found that subclade K viruses were antigenically advanced relative to the vaccine strain but that the 2025-2026 vaccine still elicited robust antibody responses in many participants. The study was presented as context for ongoing questions about vaccine match and seasonal effectiveness rather than as a definitive measure of protection.

Public health authorities across the region will be watching influenza positivity trends, strain distribution and RSV surveillance closely along with hospital and intensive care occupancy. The PAHO alert framed immediate action on vaccination, testing and surge planning as the primary tools to limit severe illness and preserve hospital capacity during a potentially intense winter respiratory season.