The "super flu" and the spike in KC-area flu cases
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Kansas City is seeing a rise in flu cases this winter, mirroring a national surge tied to the so-called super flu.
Why it matters: An unprecedented rise in flu cases comes as other sicknesses, such as the "winter vomiting bug," COVID and whooping cough, are slamming the country.
Driving the news: Flu cases remain elevated nationwide, according to the CDC.
- New data shows that there have been at least 7.5 million illnesses, 81,000 hospitalizations and 3,100 deaths from the flu so far this season.
Zoom in: Kansas City, Missouri, reported 1,060 flu cases from Dec. 21 to Dec. 27, according to the Missouri Department of Health. While the 2025–26 flu season started in early October, most of the city's 1,936 cases this season were reported in recent weeks.
- Kansas City, Kansas, saw a large spike in flu-related visits, accounting for 12% of all emergency department visits during that same week, according to the Kansas Department of Health.
Zoom out: In the week ending Dec. 20, New York saw its highest number of flu cases ever reported in a single week, per the New York State Department of Health.
The big picture: The dominant flu strain right now, a version of H3N2, emerged over the summer. In the fall, health officials in the U.K. and Canada warned that the new strain was causing a rise in hospitalizations in their countries.
- Experts were specifically worried that the current flu vaccine uses the 2024-25 subclade J and updated 2025-26 subclade J.2 as reference strains instead of subclade K, which is fueling the H3N2 strain.
- The subclade K strain features seven different mutations compared to the others, experts say.
Reality check: There isn't an official "super flu."
- The term emerges every so often, typically when there's a more severe-than-usual strain of the flu circulating, experts say.
- This time around, subclade K is being associated with the term.
- The most recent CDC tracking data shows that nearly 90% of new flu cases in the country were from subclade K, which appears to be the super flu this time around.
Symptoms associated with H3N2 aren't different from those of the common flu and include sore throat, runny nose, fever, cough, muscle aches, tiredness and chills.