Does flu vaccination reduce cardiovascular events?

This review assessed the effects of influenza vaccination on cardiovascular outcomes.

Influenza, commonly known as the “flu”, is a highly contagious respiratory infection caused by a virus that causes fever, chills, muscle pains and breathing problems. This infection can be prevented by an annual influenza vaccine, which causes antibodies (proteins produced by the immune system to fight infection) to develop in the body about two weeks after vaccination. These antibodies provide protection against the infection. Previous studies have showed that influenza infections can trigger cardiovascular events (CVE) such as heart attack, stroke and thromboembolism (obstruction of a blood vessel by a blood clot) in individuals at risk, such as patients with previously diagnosed coronary artery disease (CAD). The aim of this study was to evaluate whether influenza vaccination is associated with prevention of CVE in patients with CAD.

6 studies evaluating influenza vaccination and CVE including a total of 6735 patients were reviewed. These studies divided the patients into two arms. One arm included patients who received the influenza vaccine and the other arm included patients who received a placebo (a substance with no medical effect, used as a control when testing new drugs). Patients were followed up for an average of 7.9 months and the main parameter evaluated was the risk of CVE. 

Within one year of the study, only 2.9% of patients who received the influenza vaccine developed a major CVE compared to 4.7% of patients in the placebo group. Patients with a history of recent acute coronary syndrome (a sudden blockage of the blood supply to the heart muscle) benefitted the most from the influenza vaccine, with a risk of CVE of 10.25% versus 23.1% for patients in the placebo group. Patients who received the influenza vaccine had a lower mortality rate compared to patients in the placebo group (1.3% versus 1.7%).

In summary, this review showed that within 1 year, influenza vaccination reduced the risks of both cardiovascular events and cardiovascular-specific mortality in high-risk patients.

Talk to your doctor about annual influenza vaccination.