The Pan American Health Organization (PAHO) is urging countries across the Americas — including vulnerable Caribbean states — to sharpen their health service preparedness as the Northern Hemisphere enters its peak season for influenza and other respiratory viruses.
In a new epidemiological alert, PAHO said a mix of vaccination, stronger surveillance, hospital readiness, rapid diagnosis, and personal preventive measures will be critical to reducing infections and preventing potential strain on already stretched health systems. Caribbean health ministries, many of which face limited hospital capacity and seasonal tourism surges, are being encouraged to act early.
Global influenza activity continues to climb, driven largely by influenza A viruses, with sustained increases reported in North America. Activity remains lower elsewhere in the Americas, but PAHO notes important regional differences: in the Caribbean and Central America, influenza A(H1N1)pdm09 currently predominates, while Canada and the U.S. are seeing widespread A(H3N2) circulation — including a rise in the emerging K subclade previously detected in Europe and Asia. While severity has not increased, A(H3N2)-heavy seasons tend to disproportionately affect older adults.
Preliminary data indicates the 2025 flu vaccine is performing on par with previous years, particularly in preventing severe illness and hospitalization.
Southern Hemisphere signals ahead of Northern Winter
The Southern Hemisphere’s 2025 season, which wrapped up in early November, showed a 29% rise in reported severe acute respiratory infections compared to 2024. RSV mainly hit infants under six months, while influenza cases were concentrated among older adults. Influenza began as an A(H1N1)pdm09 season but later shifted to A(H3N2), with no increase in severity and no detection of the new K subclade.
RSV circulation began earlier than usual and reached higher levels than in 2023 and 2024, especially in parts of South America. SARS-CoV-2 activity peaked early in the year, with the XFG variant becoming dominant but without signs of increased severity.
A multi-country study found moderate vaccine protection against influenza A-related hospitalizations and stronger protection against influenza B.
What PAHO wants countries to do now
PAHO is urging governments to:
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Strengthen surveillance for influenza, RSV, and SARS-CoV-2, and ensure consistent data sharing.
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Submit samples for genomic sequencing to detect variants that may affect transmission or severity.
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Investigate unusual respiratory events immediately, including severe cases with no identified cause or outbreaks occurring outside typical seasons, in alignment with International Health Regulations.
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Review and update clinical guidelines, bolster rapid testing capacity, and ensure antivirals are available for high-risk patients.
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Prepare hospitals for a possible rise in admissions, especially in January–March when multiple viruses circulate simultaneously in tropical countries.
For Caribbean nations — where many islands are balancing chronic noncommunicable disease burdens, aging populations, and limited ICU beds — PAHO’s recommendations carry added urgency.
Vaccination still key
PAHO reiterated the importance of immunization against influenza, COVID-19, and RSV, especially for older adults, people with chronic conditions, pregnant women, young children, and health workers. Vaccination during pregnancy and the use of monoclonal antibodies for newborns have proven highly effective in reducing severe RSV disease. COVID-19 booster doses are recommended every six to twelve months for priority groups.
PAHO also emphasized that simple actions — like handwashing, covering coughs, and staying home when sick — remain among the most effective ways to slow spread.
As winter virus activity ramps up globally, PAHO says early action now can help Caribbean countries avoid preventable hospital strain later in the season.
