The U.S. Is Facing Its Worst Respiratory Virus Surge in 25 Years—Here’s What Doctors Want You to Know

Unfortunately, the CDC’s latest report points out that things are likely to get worse before they get better. Public health officials predicted that we would be in for a tough flu season after the UK and other countries had different experiences with the flu earlier this year. All of those cases are being driven by a strain of the flu known as subclade K.

Subclade K is a form of influenza A H3N2. This variant mutated seven times over the summer to create a more infectious version of the flu, according to Thomas Russo, M.D., a professor and chief of infectious diseases at the University at Buffalo in New York. “Subclade K is largely evading prior immunity,” he says. Meaning, immunity you might have built up from the flu shot or having previous strains of the flu is less effective against subclade K than it might have been against other flu strains.

Rates of people getting the flu shot are also down, which means there’s an even larger group of people who are vulnerable to getting sick—and spreading it around, Dr. Russo says. Here’s what doctors want you to know to stay safe right now.

This form of the flu is notorious for being harsh

There are different types of the flu, but flu A and flu B are the ones that fuel infections in people, Dr. Russo says. While both types circulate each year, flu A is the one that usually causes big epidemics.

Unfortunately, Dr. Russo says that flu A tends to be particularly intense, too. Still, he points out that “influenza always needs to be taken quite seriously.”

You won’t necessarily have different symptoms with subclade K, but Dr. Russo says he’s noticed more people having an intense experience with the flu this season.

Just in case you need a refresher on flu symptoms, the CDC flags these as the most common:

• Fever or feeling feverish
• Cough
• Sore throat
• Runny or stuffy nose
• Muscle or body aches
• Headaches
• Fatigue
• Vomiting and diarrhea (although this is less common)

The vaccine is still worth your time

As we mentioned above, subclade K has a few mutations that make it more infectious and better able to skirt immunity that you might have built up. That means the flu vaccine may be less effective at preventing infection than in the past.

According to data shared by the British government, the flu vaccine is 30% to 40% effective at preventing emergency room visits from the flu in adults, and up to 70% effective at keeping kids out of the ER. That doesn’t sound great—and it’s not ideal—but doctors say it’s still worth getting your flu vaccine if you haven’t already.

“The influenza vaccine, even if it does not provide high levels of protection against infection, is still effective at preventing what matters most: severe disease,” says Amesh A. Adalja, M.D., an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security.

“Flu is a serious illness. It can take even normal, healthy people and put them into the ER,” says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “It’s late to get vaccinated, but not too late.”

There are treatment options, but timing matters

There are two antiviral treatments approved for the flu: oseltamivir (Tamiflu) and baloxavir marboxil (Xofluza). While you can technically take these at any point in your illness, they work best when you start them soon after your symptoms develop.

“Flu treatments—antivirals—may shorten the duration of the illness and prevent serious complications from the flu,” says Asefeh Faraz Covelli, Ph.D., associate professor at The George Washington University School of Nursing. (In a perfect world, you’d take them within 48 hours of your symptoms starting, she says.)

Testing is crucial

If you develop symptoms of the flu—which tend to come on quickly—Dr. Russo recommends taking a home test for flu and COVID-19. (While home flu tests are less well-known than home COVID tests, there are plenty out there.) But if you only have a home COVID test around, you can take that to rule out that particular virus.

Once you have your results, call your healthcare provider about the next steps.

They’ve seen worse

There’s a lot of talk swirling around out there about how bad this flu season is, and doctors agree that cases are high. But Dr. Adalja points out he’s seen worse. “This is not the worst season in terms of hospitalizations,” he says.

Ultimately, just do your best when it comes to protecting against the flu (like masking and washing hands)—and call your doctor if you develop symptoms.