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Flu shot halves risk of heart attack or stroke in heart disease patients, Canadian study suggests

A patient gets a shot during a flu vaccine program in 2009. Jeff McIntosh / The Canadian Press

TORONTO – There may be more reasons that you think to roll up your sleeve and get the flu shot this season.

A new Canadian study suggests that the vaccine doesn’t just protect against influenza, it may reduce the risk of heart attack or stroke, especially in those who have a history of heart disease.

And the benefits of getting the flu shot may be even more pronounced for Canadians who have had a heart attack in the past year, according to the Women’s College Hospital and University of Toronto study.

Lead author Dr. Jacob Udell, a cardiologist and scientist, told Global News he hopes his findings will persuade Canadians to get vaccinated.

“If there’s very low risk involved and you can potentially protect yourself from heart attack or stroke or die from heart disease I think I can convince more patients with that kind of data,” he told Global News.

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Still, only about 50 per cent of the general population gets vaccinated. In high-risk groups, vaccination rates don’t touch 100 per cent either.

Read more: Should flu shots be mandatory for health care workers?

“Our study provides solid evidence that the flu shot helps prevent heart disease in vulnerable patients – with the best protection in the highest-risk patients. These findings are extraordinary given the potential for this vaccine to serve as a yearly preventative therapy,” he said.

Udell said that previous research had pointed to a link between patients getting the flu and facing risk of heart attack, heart failure or stroke right after getting sick.

He set out to review all of the flu trials going as far back as the 1940s when the vaccine was first looked at for his review. The data from six studies and 6,700 patients was included in Udell’s research.

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About 50 per cent of the patients were women, and one-third of the patients had heart disease. The researchers noted that if heart disease patients got the flu shot, they had a 36 per cent lower risk of a heart attack, stroke or heart failure a year later.

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If patients already had a heart attack recently, they had a 55 per cent lower risk of facing a second episode.

“There seems to be an even more robust improvement and benefit from those who were the highest risk,” Udell said.

There’s a theory at play: When patients get sick with flu, they’ll deal with aches and pain, headaches and uneasiness. Some of this is the flu virus but most of it is the immune response. That response in the bloodstream could stabilize coronary plaque or clogged arteries, Udell said.

Read more: Canadian researchers develop disease outbreak surveillance

Still, Udell and co-author Dr. Michael Farkoah say that they’ll build on this research with an international trial.

Their findings were published Tuesday afternoon in the Journal of the American Medical Association.

carmen.chai@globalnews.ca

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