A sick person holding a cup of tea.

If you skipped this year’s flu shot and then came down with the virus, you may think there’s no point in getting the vaccine now.

But you’d be wrong.

There are good reasons to get a flu shot, even if you’ve already been sick this season, says David Topham, Ph.D., a professor of microbiology and immunology at the University of Rochester and director of the New York Influenza Center of Excellence.

You can catch the flu more than once in a season, because having one “type” of flu doesn’t provide immunity against the other types that may be circulating. 

“The way your immune system sees them is very different,” Topham says.

More on flu season

Two types commonly make people ill: type A and type B. In the beginning of this flu season, most cases of flu in the U.S. were type B (an unusual development, because type A usually predominates in the early months of a season).

Now, it looks like type B flu may be beginning to wane while influenza A may be on the rise. And we’re probably far from done with flu season. According to the Centers for Disease Control and Prevention’s latest data, doctor’s visits due to flu-like illness are still on the rise, though the pace may be slowing. For the first week of February, flu illnesses jumped from 6.7 percent to 6.8 percent of all doctor’s visits, while in the last week of January, flu illnesses shot up from 5.7 percent to 6.7 percent of all doctor’s visits. 

Flu season “looks like it may be starting to level off, but it’s still going up for the country as a whole,” says Lynnette Brammer, M.P.H., an epidemiologist with the CDC’s influenza division. 

A Second Flu Can Be as Bad as the First

Getting the flu a second time can make you just as miserable as it did the first time around. And the potential for complications with the second infection is just as great as it was with the first.

Those complications can be serious, such as pneumonia and even sepsis, a potentially deadly reaction your body can have to infection.

Flu can also harm your heart. A study published in 2018 in the New England Journal of Medicine found that an individual’s heart attack risk was six times higher than usual in the seven days following a positive test for influenza. 

This may be of most concern to older adults, especially those with heart disease or who are at higher risk for heart disease because of smoking, diabetes, or other factors, says Jeff Kwong, M.D., lead author of the study and a scientist at the Institute for Clinical Evaluative Sciences in Ontario.

So Get That Flu Shot

The bottom line: If you haven’t had one yet, get a flu shot even if you already had the flu (or a bug you think might have been the flu). Although the vaccine doesn’t guarantee that you’ll avoid a second case of the flu, it will reduce the likelihood of it and its complications.

If you did get the vaccine this season, there’s no need to get a second one. Scientists believe the protection usually lasts for the whole season.

But if you’re still getting over a respiratory illness—or any kind of bug—wait until you’re fully recovered before going for the flu shot, says Topham at the University of Rochester. When you have another illness, he says, “your immune system is focused on the infection that you have and doesn’t respond as well to a vaccine.”

And keep in mind that if you’re starting to recover from the flu and symptoms worsen again, this could signal a secondary infection such as pneumonia, and you should call your doctor right away.

Your hygiene habits can also help stop the spread of flu. Remember to be diligent about washing your hands and covering any coughs or sneezes. Avoid touching your eyes and mouth to keep from transferring any germs that may be on your hands. Keeping air at 30 percent to 50 percent humidity by using a humidifier can help, too; dry air helps the flu virus live longer.

If you do get sick again, stay home to avoid infecting anyone else.