Flu Shots: 5 Common Myths

Getting a flu shot is your best protection against the flu. Let's clear up some common misunderstandings.

Myth 1: The flu vaccine can give me the flu.

It is impossible to get the flu from the vaccine. Flu vaccines are made from killed (inactivated) or weakened (attenuated) virus. So, while the vaccine helps your body produce an immune response, it cannot cause infection or illness. 

If you happen to come down with the flu shortly after getting a flu shot, you may have already been exposed to the virus. How? It takes two weeks for your body to develop the antibodies that help your body fight the strains of virus that the vaccine is made to prevent. Other (respiratory) viruses can mimic the flu, too.

Note: The vaccine that is inhaled through the nose instead of given as a shot under the skin contains live virus. It is generally not recommended for people with heart disease or other health issues.  

Myth 2:The flu vaccine has too many side effects.

The flu vaccine is proven to be very safe. Approved vaccines are also carefully monitored by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration.

The most common side effects from getting a flu shot include: 

  • Mild soreness, redness and/or swelling in the area where the shot was given
  • Muscle aches 

In rare cases, headache or low-grade fever may occur.

If you experience any of these, they are generally mild and are short-lived, only lasting only a day or two. Be sure to talk with your health care professional if you have had a severe reaction to the vaccine in the past, or if you are allergic to eggs . 

Bottom line: Most side effects from the vaccine fade against the high risk of severe illness or possible death from the flu. 

Myth 3: You don’t really need to get a flu shot each year.

Yes, you do, and here’s why: The viruses that the flu vaccine is designed to protect us against change from year to year. New vaccines are made each year (they take least six months to produce!) to match the strains (or types) of influenza viruses that research suggests will be the most common. Even if the predicted virus is a similar type to what was seen the year before, your level of protection, or immunity, against that virus wanes over time. 

Any flu infection increases the chance of complications, hospitalization or death. The best way to protect yourself and your family is to get vaccinated every year. The CDC recommends a yearly flu vaccine for most people 6 months and older—even when the current year’s viruses haven’t changed much from the year before.

Myth 4: It’s too late to get vaccinated once the flu season starts.

If you have heart disease, it’s best to get a flu shot early on, ideally by the end of October. This way, you’ll be protected early in the flu season. For this reason, many medical offices set aside some flu vaccines for people who are more prone to serious illness, including people with heart disease, a history or stroke or other health conditions.  But even if winter rolls around or the flu season has kicked into high gear, it’s not too late to get vaccinated. 

Although the flu season usually begins in October and peaks sometime between December and mid-February, flu activity can occur into April and even May. So, getting the flu vaccine at any point in the flu season can still protect you from getting sick.

Myth 5: The flu shot doesn’t really work. I still got sick after getting it.

The flu vaccine doesn’t provide complete protection. Labs make new vaccines each year to fight the three-to-four types of flu virus that scientists predict will be most common during the next flu season. Flu viruses are constantly changing, so some years the flu vaccine is a better match than others. 

But the flu shot is proven to cut the chance of getting the flu and, if you do get sick, the illness will be much milder. That’s good news when you think about the fact that the flu lasts an average of 15 days! And experts say some protection is better than none. 

Bottom line: Getting vaccinated is still the best way to protect yourself from the flu. Avoiding people with diagnosed flu and washing your hands frequently can also help you avoid getting sick this flu season. 


Published: October 2019
Medical Reviewers: Susan A. Matulevicius, MD, FACC; Vasundhara Muthu, MD
CardioSmart Editor-in-Chief: Martha Gulati, MD, FACC

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More About Flu Shots

Flu Shots Protect Hearts, Too
Flu Shots: 5 Common Myths

Learn about the building blocks of a healthy heart: CardioSmart.org/Prevention.

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