As holiday gatherings ramp up, health officials are warning of an unusually early and aggressive flu season driven by a variant dubbed the “superflu” by some media outlets.

The strain, scientifically known as influenza A(H3N2) subclade K, has become the dominant form of the virus circulating in the United States, accounting for nearly 90% of characterized H3N2 cases according to the Centers for Disease Control and Prevention (CDC).

Early, Intense Flu Season Marked by ‘Superflu’

While “superflu” is not an official scientific term and experts emphasize there’s no evidence this variant causes more severe illness than typical H3N2 strains, the subclade K has mutations that make it a poorer match for this year’s flu vaccine.

This, combined with low vaccination rates and increased indoor gatherings, is contributing to rising cases, hospitalizations, and strain on healthcare systems nationwide.

CDC data shows flu activity increasing rapidly, with at least 4.6 million illnesses, 49,000 hospitalizations, and 1,900 deaths estimated so far this season.

Positive flu tests reached 8.1% nationally in early December, and hospitalizations have risen sharply. The season started weeks earlier than usual in many areas, mirroring patterns seen in the Southern Hemisphere and parts of Europe.

What Are the Symptoms?

Symptoms of subclade K infections are similar to standard flu: high fever, cough, sore throat, body aches, fatigue, headache, and sometimes vomiting or diarrhea.

Complications can include pneumonia, especially in young children, older adults, pregnant people, and those with underlying conditions.

Experts urge vaccination even now, as the shot can still reduce severity and protect against other strains.

Early UK data suggests it prevents 70-75% of hospitalizations in children and 30-40% in adults despite the mismatch. Antiviral treatments like Tamiflu are also recommended if started early.

States with Reported Superflu (Subclade K) Cases or High Flu Activity in December 2025

The subclade K variant is circulating widely across the United States, but the following states have seen the highest levels of influenza-like illness activity or rapid increases as of mid-December CDC surveillance:

  • Colorado
  • Louisiana
  • New Jersey
  • New York (including very high activity in New York City)
  • Georgia
  • New Mexico
  • Idaho
  • Michigan
  • North Carolina
  • South Carolina
  • Massachusetts
  • Connecticut
  • Maryland

Note: Washington, D.C., is also reporting elevated activity. Flu levels are rising in most states, and experts predict widespread high activity in the coming weeks.

Local health departments, including the Georgia Department of Public Health, recommend getting vaccinated, practicing good hand hygiene, covering coughs, and staying home when sick to curb spread during the holidays.

For the latest updates, visit the CDC’s FluView or your state health department website. Stay safe this season, Georgia!

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