Studies Suggest Influenza Virus Infection Raises the Risk of Heart Attack

CDC update

February 16, 2024 — February is American Heart Month, a time for focusing on cardiovascular health and the immense burden of heart disease, the leading cause of death for men, women, and people of most racial and ethnic groups in the United States.

Heart disease is a known risk factor for developing serious flu complications. Among adults hospitalized with flu during recent flu seasons, heart disease was one of the most common chronic (long-term) conditions; about half of adults hospitalized with flu have heart disease.

But a growing body of research suggests that influenza virus infection itself could put people at increased risk for acute cardiovascular events, like heart attack and stroke.

A 2018 study found that people were six times more likely to have a heart attack in the week after being diagnosed with flu. A CDC study published in 2020 in the Annals of Internal Medicine reported that sudden, serious cardiac events are common in adults hospitalized with flu. The study, which looked at more than 80,000 adult patients hospitalized with flu over eight flu seasons, found that almost 12% of patients, or 1 in 8, had an acute cardiac event, such as acute heart failure or acute ischemic heart disease. Of these, 30% were admitted to the ICU and 7% died while in the hospital. And a study published this month in the Journal of Infectious Diseases finds that even mild illness caused by influenza virus infections are associated with a twofold increase in the risk of acute cardiovascular events in older patients.

While it's unclear exactly how influenza virus infection contributes to precipitating cardiovascular events, there is evidence that flu vaccination can help prevent those events. Flu vaccination has long been associated with lower rates of some cardiac events among people with heart disease, especially among those who have had a cardiac event in the past year. And that's supported by data from the latest randomized clinical trials. A meta-analysis published in November 2023 of studies involving more than 9,000 patients reported a 26% decreased risk of heart attacks in people who received a flu vaccine and a 33% reduction in cardiovascular deaths.

CDC recommends that everyone 6 months and older get a flu vaccine every flu season. According to CDC, flu vaccination is recommended and especially important for people at higher risk of developing serious flu complications, including people with heart disease.

During this American Heart Month, flu activity is still ongoing and CDC continues to recommend flu vaccination. It's not too late for anyone, including people with heart disease, to protect themselves from flu and its potentially serious complications, including a heart attack.