New, Severe Flu Variant Spreading Rapidly in Arizona

It's that time of year again. As the leaves and temperatures fall, we roll into the holiday season. The colder weather drives us indoors, and the holidays bring friends and family into our spaces, and we're sharing more than holiday cheer. We're swapping our favorite seasonal virus: the flu.

This Year's Flu Variant

This year, we're welcoming a new flu variant: the H3N2 “subclade K” flu strain has been detected in more than half of U.S. states, including Arizona.

This variant causes all the typical flu symptoms—fever, cough, body aches—but many people are experiencing more severe symptoms than with a typical flu.

If the symptoms escalate, especially in vulnerable groups, don't wait it out. Call a doctor or head to the emergency room.

Get our free mobile app

Is H3N2 Subclade K in Arizona?

The virus is already making the rounds in Arizona. The Centers for Disease Control and Prevention (CDC) reports that H3N2 subclade K has been detected in at least 29 states, including Arizona.

This strain was first identified around July, and it's quickly becoming the dominant flu virus. It's not just spreading across Arizona, but it's moving quickly across the U.S. and around the globe.

Public health experts are warning that the H3N2 strain tends to be more severe, and we could see higher hospitalization rates, especially among children, immunocompromised individuals, and older adults.

What Are the Symptoms of H3N2?

The symptoms of subclade K mirror the typical signs of seasonal influenza A, but they can be more intense.

Common signs include:

• Sudden fever and chills
• Body aches and headache
• Extreme fatigue
• Cough, sore throat, congestion
• Nausea, vomiting, or diarrhea (especially in children)

Doctors describe the feeling as that “hit-by-a-truck” sensation. There's not much lead-up; the symptoms appear abruptly and last for several days.

When Should Someone Seek a Doctor?

It typically takes about 5–7 days for the symptoms to run their course, but if they worsen or don't resolve after a week, seek medical care, especially if you experience any of the following:

• Trouble breathing or chest pain
• Persistent high fever
• Severe dehydration
• Confusion
• Bluish lips/face

Children, seniors, or anyone pregnant or with chronic conditions are at higher risk for complications like pneumonia or worsening of underlying diseases.

The Best Prevention

Arizona residents should expect H3N2 subclade K to circulate this winter. Consider getting a flu vaccine, and talk to a doctor about taking vitamins and supplements to help your immune system fight the good fight.