Getting a flu shot is often seen as a simple way to avoid fever, cough, and body aches during winter. However, new research suggests that the benefits of influenza vaccination go far beyond preventing infection.
A recent study published in Eurosurveillance shows that flu vaccines may also protect people from serious heart and brain problems, even if they still catch the virus.
Influenza, or the flu, is a common viral illness that spreads easily from person to person. While many people recover within a week or two, the infection can place a heavy strain on the body.
When the immune system fights the virus, it triggers inflammation. This response helps the body fight infection, but it can also affect blood vessels and the heart. For some people, especially older adults, this stress can increase the risk of heart attacks and strokes.
Scientists have known for some time that flu infection can raise the risk of these conditions in the short term. However, this new study aimed to answer an important question. Can the flu vaccine still protect people from heart and brain problems even if they become infected?
To explore this, researchers led by Croci and colleagues studied health data from Denmark. They followed 1,221 adults aged 40 and older who had a first-time hospital admission for a heart attack or stroke within about a year after a confirmed flu infection.
The researchers used detailed national health records, which allowed them to track infections, vaccinations, hospital visits, and outcomes with high accuracy.
The study covered nine flu seasons from 2014 to 2025. The average age of participants was 75, and both men and women were included. Most patients experienced a stroke, while others had a heart attack.
The findings were striking. During the first week after testing positive for influenza, the risk of being hospitalized for a stroke increased three times. The risk of a heart attack increased five times. This shows how strongly the flu can affect the cardiovascular system in a very short period.
However, the study also found something encouraging. Among people who had been vaccinated, the increased risk was cut in half. This means that even when the vaccine did not fully prevent infection, it still helped reduce the severity of its effects on the heart and brain.
Researchers used a method that compared each person to themselves at different times. This helped remove the influence of factors such as age, lifestyle, and existing health conditions. Because of this design, the results provide strong evidence of a link between flu infection, vaccination, and cardiovascular risk.
There are still some limitations. The study did not look at differences between vaccine types or how well the vaccine matched the circulating virus each year. It also did not examine whether the timing of vaccination or gender played a role. In addition, the findings may not apply exactly to countries with different healthcare systems or flu patterns.
Even so, the results have important implications. They suggest that flu vaccination offers two layers of protection. First, it lowers the chance of getting infected. Second, it reduces the risk of serious complications if infection does occur.
In reviewing these findings, it is clear that the flu vaccine may be more valuable than many people realize. It is not just about avoiding a few days of illness. It may also help protect against life-threatening conditions such as heart attacks and strokes, especially in older adults.
This study supports the idea that vaccination programs should focus on people at higher risk of cardiovascular disease. It also suggests that public health messages should highlight these wider benefits.
While more research is needed to confirm the results in other settings, the evidence points to a simple but powerful message. Getting a flu shot may help protect not only your lungs, but also your heart and brain.
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Source: Eurosurveillance (study led by Denmark researchers).
