This Year’s Flu Season is off to a Bad Start

A new strain is causing a surge in flu activity nationwide. Here’s how to stay healthy this winter

Rachel Nania,

Updated January 08, 2026

AARP

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Published August 09, 2023

/ Updated January 08, 2026

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Flu activity is rapidly increasing across the U.S., with most states now reporting high levels of illness, according to the latest data. Health experts warn the surge is likely to persist for several weeks and emphasize the importance of prescription antiviral medications, which can help reduce the severity of an infection, particularly for older adults and those at higher risk.

So far this season, there have been at least 120,000 reported hospitalizations and 5,000 deaths from flu, according to the Centers for Disease Control and Prevention (CDC). Nine of these deaths have been children.

An uptick in flu cases this time of year is not unusual, says Andy Pekosz, a professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health. They typically start climbing around the Thanksgiving holiday before peaking in the winter and subsiding in the spring.

Be on the lookout for flu symptoms

Common symptoms include:

Fever or feeling feverish
Cough
Sore throat
Runny or stuffy nose
Muscle or body aches
Headaches
Fatigue (tiredness)

Emergency warning signs can include:

Difficulty breathing
Persistent pain or pressure in the chest or abdomen
Dizziness, confusion, or inability to arouse
Seizures
Not urinating
Severe muscle pain
Severe weakness or unsteadiness
Fever or cough that improves but then returns or worsens
Worsening of chronic medical conditions

Source: CDC

What’s different about this year’s flu season, however, is a new, highly contagious strain of flu virus that’s circulating, known as subclade K. More than 90 percent of flu viruses collected and analyzed this season have been subclade K, the CDC says.

Pekosz says this particular flu strain “has mutations that may allow it to evade some, but not all, of the influenza vaccine-induced protection.”

The flu vaccine still protects

That does not mean the flu vaccine is useless, doctors and public health experts stress.

The influenza vaccine provides protection for three flu viruses: an A(H1N1) virus, an A(H3N2) virus and a B/Victoria lineage virus. So even if this year’s vaccine doesn’t turn out to be a perfect match for one of the strains, it can still provide protection against the others circulating.

“It’s also true that even when we say there’s a mismatch, the vaccine oftentimes continues to protect against severe disease better than it protects against infection,” Pekosz says. This is especially important for older adults, who are at higher risk of getting seriously sick from a flu infection.

An estimated 70 to 85 percent of seasonal flu-related deaths occur in people 65 and older, according to the CDC. This group also accounts for 50 to 70 percent of flu-related hospitalizations.

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“What the flu shot is intended to do is decrease the aggression of flu, as well as prevent you from getting the flu,” says Dr. Sindhu Aderson, an immediate care physician at Northwestern Medicine.

Nearly 44 percent of U.S. adults have received their annual flu shot, as of Dec. 27, 2025; this share is slightly higher than last year, CDC data shows.

Make a plan for flu season

If you haven’t received your flu shot yet, it’s not too late, doctors and public health experts say.

“And really, as long as there’s circulating virus out there, it’s never too late to get your vaccine,” says Ann Philbrick, a professor in the Department of Pharmaceutical Care and Health Systems at the University of Minnesota’s College of Pharmacy.

Testing is another thing to keep in mind this flu season. If you come down with symptoms — fever, sore throat and body aches are common — an at-home test or one you take in a doctor’s office can confirm influenza. This is important because if you’re positive for flu, you may be eligible for antiviral medication that can lessen the severity.

“And those [medications] are best taken early, usually in the first 48 hours of symptom onset,” Aderson says.

If you are at higher risk for severe illness from flu, talk to your doctor about these medications even before you get sick.

“I always recommend to people that if you do have a bad immune system, if you’re elderly, if you have heart problems, lung problems, even things like cirrhosis, anything affecting your immune system [and] you are sick with a fever, it’s a good idea to check in with your physician, especially with the flu or also with COVID. We can give you medication earlier on, which can help to slow down the process and keep you from getting as severe,” says Dr. Donald Bumford, an infectious disease specialist at the Cleveland Clinic.

Another thing you can do as flu activity intensifies: Call ahead to your pharmacy and check that they are stocked with flu antivirals.

“If you can do that while you’re healthy, as opposed to having to do that while you’re sick, it’s just one of those things that will make your life a lot easier, should you be unfortunate enough to get infected with influenza this year,” Pekosz adds.

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Rachel Nania is an award-winning health editor and writer at AARP.org, who covers a range of topics including diseases and treatments.

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