New Flu Variant Triggers Surge in Severe Cases Across United States

Mutated Strain Spreads Rapidly

A highly contagious new flu variant is sweeping across the United States, driving an unexpected surge in severe cases that has health experts sounding the alarm about a potentially harsh winter ahead. The mutated H3N2 strain, called "subclade K," has spread rapidly worldwide and already gained dominance in several countries in the Northern hemisphere . For the week ending December 6 — the first full week after the Thanksgiving holiday — the proportion of doctor's visits for symptoms including fever plus a cough or sore throat rose to 3.2%, according to the US Centers for Disease Control and Prevention .

Recent data indicates that 89 percent of flu viruses sampled since September 28 belonged to subclade K . This variant represents "a notable evolution in influenza A (H3N2) viruses," which some say calls into question the effectiveness of the influenza vaccine against the disease this season . Because subclade K is "quite different" from prior variants, Maniar said there is less natural immunity at the community level, further increasing the risk of spread and severity .

Other countries including Japan, China, the UK and Canada have also reported busy flu seasons. In Australia, where subclade K was first detected, there were nearly half a million confirmed flu cases, smashing the record set just the year before . The variant has now been detected in over 30 countries .

Symptoms and Severity Concerns

Health professionals are particularly concerned about the aggressive nature of this flu variant. "It's becoming evident that this is a pretty severe variant of the flu," he said. "Certainly in other parts of the world where this variant has been prevalent, it's caused some severe illness, and we're seeing an aggressive flu season already." Dr. Nita Bijoor, a family physician at Oakview Medical Associates in Greenville, said the new strain is causing more severe illness. "It's more severe, especially in children and the older population," Bijoor said .

Symptoms including a high fever, cough, sore throat, body aches and chills tend to appear all at once rather than gradually . One clue that you may have the flu is how quickly the symptoms manifest. While the common cold may develop gradually, with a scratchy throat for a day or two before you really feel unwell, the flu can be quite sudden, causing you to feel fine one moment and awful the next .

Texas has seen an uptick in hospitalizations—potentially driven by the new variant—especially in those aged 65 and older . Meanwhile, flu test positivity rates, outpatient doctor's visits and flu-related hospitalizations are all increasing, and there was one pediatric flu-associated death reported in the U.S. last week, per the CDC .

Vaccine Protection and Prevention

While the current flu vaccine wasn't specifically designed to target subclade K, health experts emphasize it still provides crucial protection. The mutated subclade K strain emerged too late for scientists to update this season's vaccine. Although it's not a perfect match to the H3N2 strain they selected, the vaccine will still offer protection throughout flu season, the experts emphasize .

The flu shot doesn't always prevent you from getting infected, but it does protect against severe symptoms, hospitalization and deaths. "The goal of vaccines is to reduce the severity of illness, and reduce the disease impact on our population," says Hopkins . This years vaccines cut the odds of needing to go to the ER or hospital for the flu by about 30% to 40% .

Beyond vaccination, experts recommend washing hands frequently and properly . Those who are not feeling well or exhibiting symptoms should "please stay home," Maniar advised — "especially if you think you are in that contagious period of the flu or any of these other illnesses that we're seeing … whether it's norovirus or COVID or RSV." "If you're not feeling well, stay home. That's a great way to recover faster and to ensure that you're not going to get others around you sick."

Looking Ahead

The timing of this outbreak raises particular concerns as the holiday season approaches. Cases are expected to rise in the coming weeks, especially after holiday gatherings . Dr Zhang warned that the upcoming holiday season may bring a further surge in respiratory illnesses. "Advanced planning and preparedness efforts, including encouraging vaccination uptake and strengthening health system readiness, are strongly recommended," she said .

If you get sick, it's a good idea to get tested since there are antiviral medications that can reduce the length and severity of illness if you start them within the first 48 hours of the illness . With flu activity rising nationwide and this more