Flu shot facts—and the 7 myths to leave behind

Every year, as flu season approaches, the same questions come up: Can the flu shot actually give you the flu? If you got vaccinated last year, do you really need another shot? And if you’re healthy, do you need one at all?

With so much information—and misinformation—circulating about the flu vaccine, it can be difficult to know what to believe.

Below, Dr. Yeseo Han, a family medicine physician with Hoag Medical Group, helps separate facts about flu shots from common myths.

Myth 1: “The flu shot can give me the flu.”

Fact: A flu shot cannot give you influenza.

“Flu shots use inactivated influenza viruses or components of the virus, so they cannot cause a flu infection,” Dr. Han says. “Some people experience mild side effects after vaccination, such as a sore arm, fatigue, headache, muscle aches or a low-grade fever, but these symptoms are generally short-lived and are different from having influenza.”

If you feel sick after getting your flu shot, you may have been exposed to a respiratory virus before you were vaccinated, or you may be experiencing another infection. It can also take about two weeks for your body to develop its best immune protection after vaccination.

Myth 2: “I got the flu shot last year, so I’m still protected.”

Fact: Flu vaccination is recommended every year.

“There are two main reasons for this,” says Dr. Han. “Flu viruses change over time, and the protection provided by vaccination decreases over time. Each year’s vaccine is reviewed and updated as needed to better match the influenza viruses expected to circulate.”

That means last year’s flu shot shouldn’t be considered a substitute for this year’s vaccination.

Myth 3: “The flu shot doesn’t work because people still get the flu.”

Fact: No vaccine provides 100% protection, and flu vaccine effectiveness can vary from season to season. But vaccination can reduce your risk of getting influenza and can help reduce the severity of illness if you do get sick.

For the 2025–26 flu season, preliminary data from the Centers for Disease Control and Prevention (CDC) found that vaccination reduced the risk of influenza-associated outpatient visits and hospitalizations in both children and adults.

“Getting vaccinated doesn’t mean you’ll never get sick,” says Dr. Han. “But it can give your immune system a head start and help reduce your risk of serious illness.”

Myth 4: “I’m healthy, so I don’t need a flu shot.”

Fact: Even healthy people can get influenza and spread it to others.

The CDC recommends annual flu vaccination for everyone 6 months and older who does not have a contraindication to vaccination. Vaccination is especially important for people at higher risk of serious flu complications, including young children, older adults, pregnant people and people with certain chronic health conditions.

Getting vaccinated can also help protect people around you who may be more vulnerable to complications from influenza.

Myth 5: “It’s already flu season, so there’s no point in getting vaccinated.”

Fact: It’s not necessarily too late.

Flu activity can continue for months, and vaccination can still be beneficial while influenza viruses are circulating. If you haven’t gotten your flu shot by the end of October, vaccination can still provide protection later in the season.

The timing can vary depending on your age, health and other factors, so talk with your health care provider about when vaccination makes sense for you.

Myth 6: “I got sick after my flu shot, so the vaccine made me sick.”

Fact: Getting sick after vaccination doesn’t necessarily mean the vaccine caused your illness.

The flu shot doesn’t protect against every respiratory virus, including the viruses that cause the common cold and other respiratory infections. And because it takes time for your immune system to build protection after vaccination, you can still become infected with influenza during that window.

“That’s one reason it’s important to think of the flu vaccine as one part of your overall approach to staying healthy during respiratory virus season,” says Dr. Han.

Myth 7: “The flu is basically just a bad cold.”

Fact: Influenza and the common cold are different illnesses, and flu can lead to serious complications.

For some people, influenza can result in complications such as pneumonia, hospitalization or, in severe cases, death. Vaccination is the best way to reduce the risk of flu and its potentially serious complications.

In fact, the CDC estimates that flu vaccination prevented approximately 180,000 flu-related hospitalizations in the United States during the 2024–25 flu season.

Remember…

It’s easy to hear a flu shot myth often enough that it starts to sound like fact. But when it comes to your health, it’s worth checking the source.

For most people 6 months and older, annual flu vaccination remains the primary way to reduce the risk of influenza and its potentially serious complications. If you have questions about whether the flu vaccine is right for you, talk with your health care provider about your individual health and vaccination needs.

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