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Health experts recently warned that this year’s flu season may be particularly bad, thanks to an aggressive strain of the virus—and the flu shot may not offer enough protection. So, do you still need the vaccine? Here's what you need to know.

December 09, 2014

On Thursday, the Centers for Disease Control and Prevention warned that this year’s flu season may be a particularly bad one, thanks to an aggressive flu strain—and the flu shot may not offer enough protection. Here’s what you need to know.

Why is flu season expected to be so bad this winter?

Each year, public health experts choose three strains of the flu virus to include in that year's batch of vaccines, based on which viruses are predicted to be most common. (Some vaccines also protect against a fourth strain.) But this year, one of the strains—an influenza A strain known as H3N2—has mutated, which means the virus has changed so much the vaccine may no longer be effective against it. When the CDC analyzed flu samples, they found that 52% of H3N2 viruses were mutated.

Unfortunately, H3N2 is also the flu strain that's most predominant so far this season, and it's historically been linked to higher rates of hospitalization and death, says William Schaffner, MD, infectious disease specialist at the Vanderbilt Medical Center in Nashville, Tennessee, and past president of the National Foundation for Infectious Disease.

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I haven’t gotten a flu shot yet. Should I even bother?

Yes! Even though H3N2 has mutated, the flu vaccine should still be effective against the rest of the strains it covers, Dr. Schaffner stresses.

And although right now the vast majority of reported flu cases are from H3N2 (roughly 90%, according to a recent CDC briefing), that may change as the season progresses: “Last year, an influenza A strain was most common for much of the winter, and then at the very end a B strain emerged and dominated,” says Susan Rehm, MD, Vice Chair of the Department of Infectious Diseases at the Cleveland Clinic.

In addition, the vaccine may still offer some protection against the mutated strain—meaning that if you do get it, your flu symptoms may not be as severe.

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Is there anything else I can do to protect myself against the flu?

Wash your hands. Schoolchildren who washed their hands twice a day reduced their risk of developing the flu by 50%, according to a 2011 study published in the journal Emerging Infectious Diseases.

The CDC recommends wetting your hands with clean, running water (it doesn’t matter if it’s hot or cold), lathering your hands all over with soap, and scrubbing them for at least 20 seconds before rinsing them well with water. If you can’t get to a sink, use a hand sanitizer that contains at least 60% alcohol.

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How do I know I have the flu, not just a really bad cold?

It’s actually pretty easy to tell if you have the flu or a cold based on your symptoms. “I tell patients to be on the alert for FACTS—that’s fever, aches, chills, tiredness, and sudden onset,” Dr. Rehm explains. “Unlike a cold—which usually starts with you feeling fine but developing a stuffy nose or a sore throat—the flu hits you quickly. You feel good all day long, and then suddenly you’re achy and your head hurts. Respiratory symptoms usually don’t develop until after you start experiencing chills and fever.”

If you do experience these signs, see your doctor immediately: they can prescribe an antiviral medication like Tamiflu, which attacks the flu virus to keep it from multiplying in your body. If you take it within 48 hours, it can help you recover faster and may even help relieve symptoms.

While some doctors’ offices offer a rapid influenza diagnostic test (they culture your nose, and results come back within 15 minutes), it’s not always necessary: “If the physician is concerned you may have flu, it’s appropriate for them to prescribe antiviral meds,” Dr. Rehm says.

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