An infectious disease professor breaks down what you need to know about this year's notoriously bad flu season and how often you can actually really get sick.

By Cassie Shortsleeve
January 23, 2018
Can You Get the Flu Twice In One Season?

For the first time in 13 years, there's widespread flu activity in every single state in the continental U.S., according to the Centers for Disease Control and Prevention (CDC), and, sadly, even healthy people have died from the flu this winter. So, needless to say, you're likely in one of three camps when it comes to the flu: You're thanking yourself for rolling up your sleeve for the vaccine; wishing you had; or, if you've already fallen victim to the virus, you might be wondering: Can I get the flu again this winter?

The short answer is one you're not going to like-that's a yes, says Nicole Bouvier, M.D., an associate professor of infectious disease at the Icahn School of Medicine at Mount Sinai in New York.

″There are four different strains of the flu that could be circulating at any given time,″ she explains. Right now, the main one in the U.S. is influenza A (H3N2). Docs have also seen cases of influenza B, but not nearly as many. And if you've suffered from one strain, you're still susceptible to infection from another, says Dr. Bouvier. That's because the different strains are different viruses-and they're not neutralized by the same antibodies.

The good news is once you've been infected by a specific strain (say influenza A H3N2), your immune response is likely strong enough that you won't get that same strain again (unless you're severely immune suppressed). ″The antibodies that your body makes (in defense of the infection) recognize the proteins on the flu virus's surface," explains Dr. Bouvier. You're usually protected from that strain for a year or so. Over time, though, those proteins mutate and change and eventually, your body doesn't recognize them, leaving you at risk for getting sick again. (Related: 5 Super-Germy Spots In the Gym That Might Make You Sick)

While you might be more worried about the flu this year, in particular, Dr. Bouvier says that this year's flu season is not ″completely out of the ordinary″ ... but that still doesn't mean it's not concerning. The number of people who are sick enough with the flu to go to the hospital is on par with the 2014–15 flu season, which was regarded as worse than usual, she notes.

So why the hype? Some of it has to do with data from the Australian flu season, which found the virus to be widespread and the vaccine to be not as effective as it's been in years past. (Australia saw the same flu strains and used the same vaccine as the U.S., so it was easy to extrapolate data, says Dr. Bouvier.)

However, it's too early for the CDC to *officially* issue an assessment of the efficacy of the vaccine this year. They'll do that later in the season, usually post-peak season, she says.

For now? Your best bet is to get a flu shot-yes, this late in the season; yes, even if you've already had the flu; and yes, even if the shot is not as effective this year as it has been in years past.

″It's entirely possible come February or March for another strain to start circulating-and those other strains are covered in the flu vaccine," says Dr. Bouvier. Plus, even if the vaccine doesn't prevent you from actually getting the flu, it can help prevent complications associated with the virus.

And make sure you keep an eye out for your flu symptoms if you do get hit with a virus once (or twice). Body aches, headaches, and fever tend to last anywhere from three to five days, says Dr. Bouvier, and respiratory symptoms like a cough can linger a week or two. But if you have trouble breathing or don't feel like yourself (you feel confused, for example), it's time to see a doc. Dr. Bouvier says the flu can progress into both viral or bacterial pneumonia.