A flu shot may not only spare you from two weeks of fatigue, nausea, and fever – it could protect your heart, too. That is the conclusion of a new study from the University of Toronto’s Women’s College Hospital, where researchers have determined that seasonal flu vaccination is associated with a lower risk of heart disease. The link may be especially strong in high-risk people with a history of adverse cardiovascular events.

Published in the Journal of the American Medical Association, the study investigated the relationship between flu shots and heart health by analyzing existing research and previous clinical trials. The team reviewed data from 6,735 subjects across six different studies. On average, participants were in their late 60s, and about one third reported previous cardiovascular problems, Reuters reported.

Compared to control subjects who received placebo shots, vaccinated subjects were significantly less likely to experience heart problems the following year. Incidence rates for placebo subjects with and without a history of cardiovascular problems were 23 percent and 5 percent respectively. For subjects who received a flu shot, the rates were 10 percent and 3 percent.

“The use of influenza vaccine was associated with a lower risk of major adverse cardiovascular events,” the researchers wrote. “The greatest treatment effect was seen among the highest-risk patients with more active coronary disease.”

The findings may serve as a new incentive for high-risk individuals who are reluctant to get the shot. "If there are those out there who for whatever reason don't get the flu shot or don't feel that they need it … this is one more reason why they might help," said Jacob Udell, senior author of the study. "Clearly if you had a recent heart attack our research is showing … they're going to derive the most protection."

David Frid, a preventative cardiologist who was not involved in the current study, added that the findings will make it easier for physicians to recommend the vaccine in doctor-patient settings. "From the clinical perspective, it gives us more supporting data to say to our patients, ‘Here's a recent study confirming what we've been telling you that if you have heart disease you should be getting the flu vaccine,'” he told reporters.

Cardiovascular disease is currently the leading cause of death in the United States, killing about 600,000 people each year. According to the U.S. Centers for Disease Control and Prevention (CDC), that is about one-fourth of all fatalities. On average, deaths and illnesses associated with coronary heart disease cost the nation $109 billion annually.

Source: Udell JA, Zawi R, Bhatt DL, et al. Association Between Influenza Vaccination and Cardiovascular Outcomes in High-Risk Patients: A Meta-analysis. JAMA.2013;310(16):1711-1720. doi:10.1001/jama.2013.279206