Flu activity surged in December 2025 and January 2026 during heavy holiday travel and celebrations. The increase appears in the latest data from the Centers for Disease Control and Prevention. CDC officials say flu transmission often accelerates during crowded winter gatherings.
The CDC reports at least 11 million illnesses this flu season. Hospitalizations reached 120,000 and fatalities climbed to 5,000 nationwide. These figures reflect surveillance data collected through December 27, 2025.
Health officials warn flu activity will continue rising as winter progresses. Experts say seasonal peaks tend to arrive after major holidays and travel periods. This trend raises concern for hospitals already facing staffing and capacity pressures.
What Strain is Causing the Surge?
A significant portion of cases involve a strain called subclade K. Subclade K is a novel variant linked to the H3N2 influenza lineage. H3N2 itself is a subtype of influenza A viruses.
Subclade K has circulated internationally since the summer of 2025. Global spread indicates the strain gained momentum before the U.S. season. This pattern raises concerns about immune escape and rapid transmission.
The CDC analyzed 163 H3N2 samples collected during September 2025. Genetic sorting showed 89% belonged to subclade K. These findings suggest the strain quickly became dominant.
Who is Most Vulnerable?
Pediatric flu deaths have already occurred during this season. Nine children have died from flu-related complications so far. Each pediatric death raises alarms among public health experts.
Last flu season saw 288 pediatric deaths across the United States. That total matched child fatalities during the 2009 H1N1 pandemic. The comparison highlights the severe impact of seasonal influenza.
CDC research shows most pediatric flu deaths involved unvaccinated children. Around 90% of pediatric deaths in 2024 lacked vaccination. Officials stress vaccination remains the strongest protective measure for children.
Where Is Flu Hitting Hard?
New York State reported unprecedented flu activity in late December. State officials recorded the highest weekly flu cases ever documented. Mandatory flu reporting in New York began in 2004.
By late December, New York logged more than 70,000 cases. This represented the largest single-week total in state history. The number marked a 38 percent increase from the prior week.
Total flu cases statewide rose to 189,312 by December’s end. Hospitalizations also surged sharply during the same period. Weekly hospital admissions climbed from 2,251 to 3,666 patients.
That increase represents a 63% rise in flu hospitalizations. Hospitals reported growing strain from the rapid influx of patients. Health systems warned resources could tighten if trends persist.
How to Prevent Spread
Health experts emphasize awareness and prevention remain essential. They recommend masking in crowded public places during high transmission. Handwashing with soap and warm water also reduces infection risk.
Officials stress prevention protects individuals and broader communities. High vaccination coverage helps limit hospital strain and fatalities. Public health experts urge continued vigilance throughout the season.
Conclusion
Flu activity continues rising nationwide, driven by travel, subclade K, and low vaccination. Millions of illnesses, rising hospitalizations, pediatric deaths, and record state surges highlight risk. Vaccination, masking, and hygiene remain essential to prevent severe illness and deaths.
Have an upcoming trip? Passport Health offers a wide variety of options to help keep you safe from disease, including vaccines. Call or book online to schedule your appointment today.
Logan Hamilton is a health and wellness freelance writer for hire. He’s passionate about crafting crystal-clear, captivating, and credible content that elevates brands and establishes trust. When not writing, Logan can be found hiking, sticking his nose in bizarre books, or playing drums in a local rock band. Find him at loganjameshamilton.com.
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