Heart Attack Risk

The flu vaccine could also double as a heart attack deterrent according to a recent study published to The New England Journal of Medicine.

According to the study, people are more susceptible to a heart attack, or acute myocardial infarction, when they're suffering from the effects of the influenza virus. The researchers analyzed 20,000 cases in Ontario, Canada involving adults diagnosed with influenza between 2009 and 2014. Surprisingly, they discovered 332 patients had been hospitalized for a heart attack in the year before or after their influenza diagnosis.

You're 6.3 times more likely to have a heart attack in the three days following a flu diagnosis. Credit: Institute for Clinical Evaluative Sciences.

"We found that you're six times more likely to have a heart attack during the week after being diagnosed with influenza, compared to the year before or after the infection," Dr. Jeff Kwong, lead author on the study and a scientist at the Institute for Clinical Evaluative Sciences (ICES) in Toronto, told NPR. Kwong elaborated that when someone has the flu: "There's inflammation going on, and your body is under a lot of stress." Dropping oxygen levels and bloods pressure increase the risk of clots forming in bloods vessels serving the heart.

According to the LA Times, Kwong and his team observed that the risk of a heart attack was 6.3 times greater during the first three days following a flu diagnosis, and 5.8 times greater during the four days after that.

Deadly Flu Season

While everyone is potentially at risk of having a heart attack when afflicted with the flu, Kwong told NPR that it's very unlikely that it would happen to a younger person. The risk may be higher for adults 65 and older.

“People at risk of heart disease should take precautions to prevent respiratory infections, and especially influenza, through measures including vaccinations and handwashing,” said Kwong in a post on ICES. The increased risk is also not specific to people with the flu, but rather anyone affected by a virus that impacts the respiratory system.

Further clarification on the link between influenza and heart attacks comes at an apt time, as the 2017-2018 flu season is the most widespread on record. According to The Washington Post, the virus has already spread across the entire continental U.S. and caused more child deaths than expected for this time of year.

"I think the simplest way to describe it is that flu is everywhere in the U.S. right now," said Daniel Jernigan, director of the Influenza Division at the Centers for Disease Control and Prevention in a press release. Jernigan's team has been keeping tabs on the flu for 13 years, and this is the first year they've observed widespread activity in all of the continental U.S.

The rapid spread of influenza this early in the year could see more doctors pushing the idea of community immunity. Community immunity, also called herd immunity, suggests that when enough people are vaccinated against a disease, the harder it will be for the germs to spread. This protects the people who cannot, or will not, receive vaccinations from getting sick.

Eventually the disease could become rarer, or be wiped out entirely, according to the U.S. Department of Health & Human Services. Reaching the threshold for herd immunity against the flu could mitigate the severity of next year's flu season.

But for now, doctors are continuing to recommend that everyone get a flu shot — not only for the collective good of achieving herd immunity, but for the personal benefit of decreasing one's heart attack risk.

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