What to know about the Subclade K variant driving this year’s flu season
January 27, 2026Categories: Blog Posts
If it feels like everyone around you is getting sick this winter, you’re not imagining it—the current flu season has been especially severe. According to the CDC, there have so far been over 18 million reported flu cases, 230,000 flu-related hospitalizations and 9,300 deaths. But why is this season hitting harder than usual?
Accounting for more than 90% of cases is the Subclade K variant—a new influenza A(H3N2) that has been the dominant virus in circulation. Gul Madison, MD, an infectious disease specialist at Mercy Fitzgerald Hospital, explains that Subclade K’s ever-evolving nature makes it highly contagious.
“This virus is different in the sense that it has at least 10 mutations, by this way changing its structure and evading our immune system,” says Dr. Madison.
Symptoms of the flu—including Subclade K—are fever, sore throat, cough, body and muscle aches, headaches and weakness. Children with the flu often experience diarrhea and vomiting as well.
Most people with the flu do not need to see a health care provider, with symptoms resolving on their own at home. However, there are some instances when medical intervention is necessary.
“When we see potential signs of complications, then we should be seeking medical attention,” says Dr. Madison. “Fever not resolving after three to five days; worsening of symptoms or new symptoms starting after three to five days, including fever, development of cough or shortness of breath. These are warning signs that we should be seeking attention.”
There are a few simple ways to protect yourself and your family from contracting the flu. These include sleeping and eating well, exercising and having good hygiene practices, such as washing your hands, and cleaning frequently touched surfaces at home and work. It’s also important to cover coughs and sneezes, as the flu is mainly spread through respiratory droplets.
The main form of prevention is the flu vaccine, which helps reduce symptoms and the overall severity of the virus. Vaccinations are available at Trinity Health Mid-Atlantic Medical Group’s primary care locations.