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7 myths about the flu shot

Sarah Bradley writer headshot By | September 9, 2019
Medically reviewed by Karen Berger, Pharm.D.

Every fall, the flu virus starts circulating… and so do a slew of myths, rumors, and half-truths about this nasty illness and the vaccine designed to prevent it. They spread from person to person, just like influenza itself. All the misinformation gives loads of people easy reasons not to get the flu shot.

The flu is a significant public health issue that commonly affects literally millions of Americans each year. Virtually every health institution, from the Centers for Disease Control and Prevention (CDC) to the World Health Organization (WHO), recommends that healthy people six months of age and older get an annual flu shot. So, it’s important to separate fact from fiction.

We asked an infectious disease specialist and a primary care provider about seven of the most popular myths about the flu shot. Here’s what they had to say. 

Myth #1: The flu shot will give me the flu.

This is the myth that just won’t go away. No matter how many times health care professionals debunk it, plenty of people still believe that the flu shot will inject them with a weakened, live version of the influenza virus in order to build up their immunity, and therefore give them the flu. And once again, it’s just not true. The flu shot isn’t dangerous.

“The flu vaccine doesn’t give you the flu because it’s a killed virus, not a live one,” says Christelle Ilboudo, MD, an infectious disease specialist at the University of Missouri Health Care system. “It can’t lead to disease.”

So why did you feel crummy after your last flu shot? Dr. Ilboudo says there are two likely explanations: one, feeling ill after the injection is a natural immune response common to many vaccinations, and two, you’re getting the shot at a time when viral illnesses abound. 

“Some people are already infected with the flu before they get the vaccine, so then they get sick [coincidentally right after the shot],” she explains. 

Additionally, the influenza vaccine takes two weeks to become fully effective—so you could be exposed to the virus before the vaccine is able to fully protect you from illness. Either way, though, the shot itself isn’t to blame.

RELATED: Flu shot 101—Everything you need to know about the flu shot

Myth #2: I never get the flu, so I don’t need a vaccine.

Dr. Ilboudo says she hears this myth quite a bit, and though common, it’s not a good reason not to get the flu vaccination. Never having the flu before doesn’t mean you won’t ever get it—and your symptoms could include anything from mild sniffles and sneezes to low-grade fever, body and muscle aches, headache, sore throat, and cough, depending on how severely the virus affects you. 

She also emphasizes that while your immune system might be top notch, the same can’t be said for everyone you come into contact with: “When you get a flu shot, you protect yourself and those around you who have a higher risk of flu complications, like asthmatics, diabetics, and pregnant women.”

Even if you’re the type to never get sick, there are no guarantees during flu season. What infects you as a minor illness could cause major problems for your immunocompromised family members, friends, coworkers, and neighbors if you spread it around.

Myth #3: The flu is just a bad cold…why would I get a vaccine for it?

Speaking of minor illnesses, the flu actually doesn’t fall into that category. 

“Influenza is a deadly virus that kills thousands of people every year,” says Joshua Septimus, MD, an internist at Houston Methodist. “Influenza can also cause serious illnesses that require hospitalization, such as pneumonia.”

Since 2010, the CDC estimates anywhere from 140,000 to 960,000 flu-related hospitalizations every year and about 12,000 to 79,000 flu-related deaths in the United States. Meanwhile, Dr. Septimus explains, the common cold isn’t life-threatening and rarely results in additional let alone serious complications. 

Myth #4: I got a flu shot last year, I don’t need another one.

The faulty thinking here lies in the way the flu vaccine works. According to Dr. Septimus, the viral strains that circulate each fall and winter change from year to year, and the immunizations distributed to doctor’s offices, health clinics, and pharmacies change, too (to target the flu strains predicted to spread the most widely). Even if the formulations didn’t change, Dr. Septimus says, the immunity provided by the influenza vaccination wanes over the course of the year. 

Meaning, you can’t coast along on the benefits of last year’s shot.

Myth #5: I’m allergic to eggs, so I can’t get the flu shot.

Most flu shots produced today use an egg-based manufacturing process that leaves trace amounts of egg protein behind. So, many people with egg allergies assume the vaccine isn’t safe for them. Dr. Ilboudo says that’s not the case.

“The vaccine doesn’t actually contain eggs [in whole form] and people with mild egg allergies can still receive the vaccine,” she asserts.

That said, if you’ve ever had an allergic reaction to a flu shot before, you should talk to your provider before receiving one to avoid any unnecessary complications. Common symptoms indicative of an egg allergy include hives, nasal congestion, vomiting, and—rarely—anaphylaxis.

Myth #6: The vaccine is harmful or could cause serious side effects.

We’ve all heard rumors about the “toxic chemicals” present in vaccines and how they can cause serious side effects (including autism, a theory that has been disproven repeatedly but still spreads in certain circles). But Dr. Septimus says there are no harmful ingredients in the flu shot and these reasons not to get a flu shot are just baseless rumors.

“This is a common myth promoted by anti-vaccine fringe elements—the same people responsible for the current deadly measles outbreak,” he asserts. “The most common side effect of the flu shot is a sore arm and more serious side effects are vanishingly rare.” 

For more information on adverse effects to vaccines, search the Vaccine Adverse Event Reporting System

Myth #7: The flu shot isn’t 100% effective, so why bother?

On average the flu shot lowers the risk of flu illness between 40% to 60%, according to the CDC. Some people interpret that as a vaccine “failure” and use it as an excuse to skip the shot. It’s important to remember, though, that no medical intervention is 100% effective. Some protection is always better than no protection.

“Even in a year where the vaccine is only 50%  effective, that’s a 50% reduction [in illness],” Dr. Septimus says. “If a medical intervention would reduce the risk of a heart attack by 50%, we would all choose it!”