Flu shots may help protect you from far more than the flu. A new study suggests that the vaccine may also lower risk for heart attacks and strokes.
Because prior studies on the topic had been conflicting, an international group of researchers looked at the results of a dozen different studies to see if they could pinpoint the flu vaccine’s effect on heart health. They reported in the Journal of the American Medical Association that they found “a consistent association between influenza vaccination and a lower risk of cardiovascular events.”
Data from five of the studies followed approximately 3,000 people who got the flu vaccine and about 3,000 who instead received a placebo vaccine or did not receive any vaccine. Of those who did not receive the flu vaccine, 4.7% had a major cardiovascular event, compared to 2.9% of people who got the real vaccine. This means that people who got the flu shot reduced their risk by 36%. The benefit was even greater for people with coronary artery disease. For people who have had a heart attack in the past, the flu vaccine cut the risk of another major cardiovascular event by over 50%.
Prior studies have linked influenza infection with increased risk of strokes, heart failure and heart disease. Experts believe that the physical stress the influenza virus puts the body through may be responsible for these effects. While the mechanism is still not completely understood, the virus may cause the heart muscle to become inflamed or trigger the rupture of arterial plaques that cause heart attacks. In that case, the vaccine likely helps by reducing the likelihood or severity of the flu, rather than by exerting a separate effect on the heart.