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Flu vaccine lowers heart attack risk, study finds

Looking for another reason to get that yearly flu shot? It could lower your risk of having a heart attack, stroke, or other serious heart complication—especially if you already have heart disease. That’s the finding of a study published Tuesday in the Journal of the American Medical Association.

The researchers reviewed five previously published clinicial trials involving nearly 6,500 volunteers with an average age of 67. They found that those who had the influenza vaccine were 36 percent less likely to have a life-threatening heart attack, stroke, or heart failure within a year of being vaccinated, compared with those who received a placebo vaccine. Out of those who received the placebo, 4.7 percent had a heart event compared with 2.9 percent who received a flu shot.

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When the researchers isolated only those who previously had a heart attack or unstable chest pain they found that the immunization offered an even greater benefit: about 10 percent of the heart patients who were vaccinated developed a serious heart complication during the study compared with 23 percent of those who had a placebo shot.

Why would the flu vaccine lower a person’s heart attack risk?

The study authors said they didn’t know for certain but that it might have something to do with flu infections causing inflammation that might increase the likelihood of heart rhythm abnormalities, fluid buildup around the heart or a rupture of artery plaque that would block bloodflow to the heart.

But Dr. Kathleen Neuzil, a vaccine researcher who wrote an editorial that accompanied the study, emphasized that the analysis can’t conclude for certain that the vaccine actually reduced heart complications because some of the studies weren’t of high enough quality.

“Regardless of whether influenza vaccine reduces cardiovascular disease,” Neuzil wrote, “the known morbidity of influenza in older adults...and the known efficacy of the vaccine warrant its use.”

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