How Do Flu Shots Work?
Flu viruses change from year to year. That’s why the vaccine is updated ahead of each flu season to match the strains, or types, of flu viruses that researchers think will be the most common for the upcoming season. That’s why you need to get a flu shot every year.
Getting one is super important if you have heart disease or recently had a heart attack or stroke. The flu shot has been shown to lower the risk or chance of:
- Secondary infections like pneumonia that can stress the heart even more
- Heart attack, stroke and even dying from heart or blood vessel disease
- Among people with heart disease, it significant cuts the risk of flu-related heart events
- Another heart attack or stroke (among people who’ve recently had one)
- Hospitalization for flu-related health problems, including new or worsening heart issues
- Dying from heart-related causes
The flu vaccine is given as an injection into the muscle of your upper arm. After you get it, your body will develop antibodies to help you fight off the strains of the virus that the vaccine targets. You’re protected in about two weeks after being vaccinated.
Not All Flu Shots Are the Same
If you are 65 or older, experts recommend that you get 1 of 3 flu vaccines that can give better protection against the flu and related complications, including heart issues. As we age, our immune system isn’t as strong. These flu vaccines are more effective than the standard vaccine and prompt a better immune response.
Talk with your doctor about:
- How to get your flu vaccine before flu activity ramps up and
- Which flu vaccine is best for you based on your age and health
There also is a spray nasal flu vaccine. Unlike the flu shot, it contains live – but weakened – virus. It is not recommended for adults 65+, pregnant women or people with certain health conditions.
- Last Edited 09/30/2025