What to know about the flu shot, heart disease and stroke

Protect your heart and brain, especially if you’re living with heart disease or stroke
Nurse places bandage on upper arm of young woman

If you’ve experienced heart disease or stroke, or if you’re at risk for these conditions, a bout of the flu can increase your chances of having a heart attack or stroke. A flu shot can help. More on that later.

“The flu stresses the body,” says Dr. Craig Jenne, a Heart & Stroke funded researcher who’s an associate professor in the Department of Microbiology, Immunology and Infectious Diseases at the University of Calgary. 

In fact, the viral illness known as influenza or flu leads to about 12,200 hospitalizations and 3,500 deaths in Canada every year. The most vulnerable include people over 65 and those with other health conditions, including heart disease.

Flu and cardiac events

One Canadian study found that people were six times more likely to have a heart attack while they had the flu. 

Other long-term research shows that having complications from the flu, such as pneumonia, increased the risk of cardiac events for years following the infection. This was true even for people without any previous risk factors, says Dr. Jenne, the Canada Research Chair in Imaging Approaches Towards Studying Infection. 


<p>Dr. Craig Jenne (far right) with his research team at the University of Calgary.</p>

Dr. Craig Jenne (far right) with his research team at the University of Calgary.

His own research has found that flu triggers blood clotting and inflammation in mice – mechanisms associated with heart disease and stroke. This may explain why the flu can increase your chances of having a cardiac event or a stroke in the short term. And, over time, having the flu can increase the risk of heart disease and stroke in healthy people too.

Flu shot reduces severity

Luckily, the flu shot is an effective way to reduce strain on the cardiovascular system. A review study showed that getting the vaccine reduced incidence and severity of cardiovascular disease and stroke.

Dr. Jenne notes that the flu vaccine is not always a good match for the viruses circulating that year, but it still seems to help. “Even if it doesn’t stop you from getting the flu, a flu shot lowers the severity of the impact.”

And you are also protecting people around you who may be at risk, he adds. “It’s four minutes out of your life.”

Talk to your healthcare provider or pharmacist for more information about the flu shot.

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