Double duty: Annual flu shot also may reduce risk of heart attack

March 14, 2019

Now there’s another good reason to get your annual flu shot. A study conducted at Icahn School of Medicine  at Mount Sinai in New York City has found that, not only can the vaccine protect you from influenza; it may even prevent you from having a heart attack, Medical News Net reports.

The research initiative—which will be discussed at the American College of Cardiology’s 68th Annual Scientific Session, in New Orleans from March 16 to 18—involved searching through nearly 30 million hospital records.

What the clinicians found was that people who got a flu shot while hospitalized had a 10% lower risk of having a heart attack that year; compared to people who visited a hospital, but did not get the vaccine during their stay.

The study is the largest to date to investigate the relationship between the influenza vaccination and heart attacks. The findings are consistent with previous research suggesting getting a flu vaccine can reduce a person’s risk of major cardiovascular problems.

“You don’t need to be a medical professional to see this data and understand the importance of getting the flu vaccine,” said the study’s lead author Mariam Khandaker, MD, an internal medicine resident at Icahn School of Medicine. “The flu vaccine should be considered primary prevention for heart attack, just like controlling your blood pressure, diabetes, and cholesterol.”

Drawing on a data set known as the National Inpatient Sample, the researchers analyzed the records of nearly 30 million adult patients who visited a hospital in the United States in 2014. They divided patients into those who had received a flu vaccine while hospitalized during that year and those who had not. They then analyzed the proportion of each group who, at any point in 2014, visited the hospital for either a heart attack or unstable angina, chest pain caused by a partial blockage of the heart’s arteries.

About 2% of patients had received a flu shot while hospitalized and 98% had not (the data set did not include flu shots received outside of a hospital setting). Of those who had not received a flu vaccine, 4% had a heart attack or unstable angina. Of those who had gotten the flu shot, only 3% had a heart attack or unstable angina.

This is a statistically significant difference due to the large size of the data set. In particular, the vaccinated patients had about 5,000 fewer cases of heart attacks than would have been expected without the vaccine. After adjusting for several confounding variables, vaccination was associated with a 10% reduction in the risk of having a heart attack.

Heart attacks and unstable angina occur when plaque breaks free from the lining of a blood vessel and creates a clog in one or more of the heart’s arteries, fully or partially blocking the flow of blood to the heart. Having the flu can cause inflammation in the blood vessels, which increases the likelihood that plaque will rupture. The flu can also cause physiological effects, such as decreased oxygen supply and increased heart rate, which can exacerbate existing heart conditions.

“By getting the flu vaccine, you can help to prevent this cascade of events from taking place and, thus, prevent a heart attack,” Khandaker said. “While a person can still contract some strains of influenza even after getting a flu shot, the vaccine can lower the severity of the illness and, thus, still potentially help to prevent a heart attack.”

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