4 Surprising Benefits of the Flu Shot

His most intriguing hypothesis is that vaccines alter the brain’s overall defenses. “There’s good evidence that when we get these vaccines, they help us make antibodies to the specific pathogen — the influenza virus,” he says. “But they may also modify the immune system in such a way that it’s better at either cleaning up amyloid and tau [the proteins responsible for the plaques and tangles that are the hallmarks of Alzheimer’s] or by preventing these proteins from building up in the first place.” 

2. The shot is linked to a stronger heart

A history of heart disease or a stroke can make flu more likely and more dangerous. In addition, flu can be a trigger for heart attacks and strokes in people at high risk for them. 

According to a Canadian study, people who got the flu were six times more likely to have a heart attack within a week of getting the diagnosis. And Columbia University researchers saw a significant jump in strokes in the month after flu cases, according to research published in the American Heart Association’s journal Stroke. 

A flu shot can also spare you the potential heart harms. A study led by the University of Toronto that incorporated six previous studies covering more than 9,000 patients showed that people who received a flu vaccine had a 34 percent lower risk of a major cardiovascular event in the 12 months following vaccination.

Higher-risk vaccinated individuals with acute coronary syndrome — a group of conditions that abruptly stop blood flow to the heart — had a 45 percent risk reduction of major cardiovascular event, and a 56 percent reduced risk of dying from heart disease in the year after they got the shot, according to the findings, which appear in JAMA Network Open. 

How the flu shot protects the heart isn’t fully known, but it may have to do with the plaques that build up on artery walls of people with heart disease. The body’s immune response to the flu creates inflammation that is believed to disrupt these fat deposits, causing blood clots that may trigger heart attacks and strokes.

“The vaccine may interact with the body’s immune system and inflammatory processes to help stabilize plaques that might be present in blood vessels, thus preventing these plaques from rupturing and causing further problems,” says researcher Bahar Behrouzi. 

3. It could curb complications from other chronic conditions

Like heart disease, some chronic health conditions make you more prone to flu and its harmful effects. For people with diabetes or chronic lung diseases, like chronic obstructive pulmonary disease (COPD), an annual flu shot is one of the best ways to avoid aggravating these underlying health problems. 

Evidence comes from researchers at the University of Minnesota Medical School and the Veterans Affairs Medical Center in Minneapolis who followed people age 65 and older in a large health plan who had respiratory diseases over three flu seasons. Their findings, published in Annals of Internal Medicine, show that patients who got vaccinated were 52 percent less likely to be hospitalized for pneumonia or flu and 70 percent less likely to die from these diseases during that period.

Similarly, a UK study showed that when people with diabetes got the jab, it reduced their chances of being hospitalized by almost 80 percent during the two flu seasons that were studied.

4. It may make for a longer life

The flu shot might even increase your life span. The evidence: In a study out of Toronto, researchers looked at more than 54,000 people age 65 and older who had been tested for the flu between 2010 and 2016. They found that those who received the flu shot were less likely to die from any cause over the multiyear period.

“In large databases from Ontario, we found that influenza vaccines may reduce the chances of older adults dying by as much as 34 percent,” says study author Jeff Kwong, M.D., with the University of Toronto.

Flu shots likely protect older adults from dying simply by preventing the infection in the first place and by preventing those who do get infected from getting very sick from the virus, Kwong says.

While getting the jab is critical, Kwong also recommends wearing face masks, washing hands and avoiding sick people during flu season to prevent complications from both flu and other respiratory illnesses that tend to cause problems in the fall and winter, such as COVID-19.

“In many places in the world, when mask-wearing was made mandatory, influenza basically disappeared,” Kwong says. “Vaccines should be thought of as one layer of protection, and the more layers one has, the better.” 

Editor’s Note: This story, first published Oct. 3, 2022, has been updated to reflect new information.