Can I get the flu if I've had a flu shot?

Dr. Alan Young, MD
Family Practitioner

You can get the flu if you’ve had a flu shot. Getting a flu shot does significantly lower your risk of getting the flu, but you can still get it. The flu vaccine is better some years than others, but regardless, you can still get the flu.

There's still a benefit to getting a flu shot. Those who received the vaccine and get the flu often have milder cases of the infection than people who were not vaccinated.

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Stacy Wiegman, PharmD
Pharmacy Specialist

The risk of getting the flu after taking the flu shot is low. Studies from previous years show that the flu vaccine, whether given as a shot or nasal spray, appears to protect up to 60% of people from getting sick when the vaccine is a good match to the circulating viruses. The effectiveness of the vaccine during any given flu season depends on the health of the person who receives it and how well-matched the viruses in the vaccine are to the particular viruses circulating at the time.

People whose immune systems are compromised and elderly people are most likely to contract the flu, even if they've been vaccinated, according to the Centers for Disease Control and Prevention. The vaccine itself does not cause the flu. 

You can still get the flu if you've had a flu shot because it will not provide 100% protection against the flu. The flu vaccine is not foolproof. When the vaccine and the circulating viruses are similar, the vaccine can prevent the flu among 70% to 90% of healthy adults under 65. Even if you do get the flu, the vaccine can still protect you against flu-related complications by minimizing the severity of the illness. And, contrary to flu myths out there, you cannot get the flu from a flu shot or the nasal vaccine.

You can still get the flu, even if you got a flu vaccine. The flu shot lowers your chances of getting influenza, and if you do get the flu, it's likely to be less severe.

There are over a hundred strains of influenza. The shot usually protects against the top three or four strains, so there are a number of strains not covered. However, some of these strains are close enough that the flu vaccine will still offer some protection. Sometimes, the predictions are wrong, and the wrong strains are in the flu shot for that particular year. In addition, not everyone who gets the shot will be immunized. These people are called non-responders. This changes from year to year, but around 90 percent of people will respond to the shot, so there are some people who even though they got the shot are not protected.

Dr. Diana K. Blythe, MD

You cannot get the flu, or influenza, from the flu shot. However, you can still get the flu if you are exposed before protection starts.

After getting the flu shot, your body needs around two weeks to create an immune response capable of fighting off the flu. If you get the flu shot and then get exposed to the flu virus a week later, you may not have the full protection that the flu shot would have given you the next week. 

In addition, the flu shot only offers protection against the three most common flu types of the season. If you are exposed to another type of the flu, you will not have protection. Because of this, it is important to get your flu shot every flu season in order to get protection from the flu types of that particular season.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.