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Flu Shot Lowers Heart Disease Risk, Say Researchers

By Annie Hauser
Published: October 22, 2013

Chilly fall temperatures mark the beginning of the flu season, which officially runs from October to April. What do you need to know about this year’s flu? Click through to find out. (Thinkstock/Digital Vision)

  • Slow Starts Don't Guarantee Mild Seasons
  • The Flu Shot Offers Other Benefits
  • Get Your Flu Shot Early
  • Expect the Unexpected
  • It’s a Highly Contagious Virus
  • New Vaccine Might Offer More Protection
  • Seniors Need Extra Protection
  • Get the Vaccine, Regardless of Allergies
  • The Bird Flu Still Threatens
  • A Universal Vaccine May Be Near
  • Don’t Go to Work if You Have the Flu

Fall is here, and with it, the official start of the 2013 flu season. 

Public health officials urge anyone over the age of 6 months to receive some form of the flu vaccine, citing its ability not only to prevent the flu, but also stave off the virus' deadly complications in those who are infected.

Some also flag another reason, that people who receive flu shots have a lower risk of heart failure or heart attack — a finding University of Toronto researchers report in the latest issue of the Journal of the American Medical Association.

(ABOVE: Flu Season 2013-2014: What You Need to Know)

Researchers performed a meta-analysis of five randomized clinical trials of the influenza vaccine and its association with the prevention of cardiac events. The five trials showed that 2.9 percent of patients who received the flu shot experienced a cardiac event, compared to 4.7 percent of the patients in the control groups, showing a significant heart-risk reduction in patients who received a flu shot. (An absolute risk difference of 1.74 percent.)

Among patients with pre-existing heart disease, the absolute risk difference was 12.9 percent in favor of the flu shot. 

This is an important study because it highlights the benefit of the flu vaccine, Curtis Rimmerman, MD, a cardiologist at the Cleveland Clinic told Weather.com. But because so few randomized controlled trials have been conducted on the topic, more research is needed into the association, he said.

“It’s unknown why the link exists, but we have some theories,” he said. Quite simply, whether because of advanced age or another condition, such as type 2 diabetes, someone who has a high risk for the flu may also have an elevated risk of heart disease, he said. Contracting the flu also causes inflammation in the body, raising heart disease risk, some previous studies have found. There are may be a relationship between the flu, flu shots and blood clots, he said.

Healthier people — who therefore most likely have a lower risk of heart disease — might also be more likely to get vaccinated in the first place, further exacerbating the association, Steven Nissen, MD, MACC, the chairman of the department of cardiovascular medicine at the Cleveland Clinic said in an interview to Weather.com earlier this year. Dr. Nissen's comments came in response to a small epidemiological study on the flu shot and heart disease risk.

"People who choose to be vaccinated [against influenza] are very different from people who choose not to," Dr. Nissen said. "They are much more health conscious; it's likely they participate in other healthy behaviors, so it's not at all surprising that they would be healthier [and therefore less likely to have a heart attack]."

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