Getting a flu shot protects your heart too — not just your lungs
Influenza kills tens of thousands of people every year in the US alone — and many of those deaths aren’t directly from the infection.
Infections trigger immune responses that temporarily damage blood vessels and raise the risk of heart attacks and strokes. That mechanism has been known for some time, but new evidence quantifies how large that effect is specifically with influenza — and how effectively vaccination can counteract it. People who were vaccinated but still contracted the flu showed significantly fewer cardiovascular complications than unvaccinated people who got infected.
For older adults, this is especially consequential. The aging immune system responds to infections differently: more aggressively, less precisely, and with more prolonged inflammatory damage. Chronic low-grade inflammation — what researchers call inflammaging — is already one of the central processes driving biological aging and age-related disease. A flu infection adds fuel to that fire. The combination of an already stressed cardiovascular system and a dysregulated immune response can be deadly.
Inflammation as the hidden culprit
The connection between infections and cardiovascular disease is gaining serious attention in longevity science. Researchers have argued that infections — even mild ones — accelerate biological aging by leaving behind epigenetic damage and elevated inflammatory markers. Every flu season someone endures without vaccination may be more than just a week of feeling terrible. It could represent a cumulative assault on the health of blood vessels and organs.
Vaccination doesn’t just reduce the chance of severe illness. It also dampens the intensity of the immune response when infection does occur. That second effect — a more measured inflammatory reaction — explains why vaccinated people who get sick anyway sustain less cardiovascular damage. It’s an indirect form of protection that rarely gets emphasized in public health messaging about vaccines.
A simple intervention with compounding returns
From a longevity perspective, this is a striking finding. Flu vaccination is cheap, widely available, and has decades of safety data behind it. If it also reduces the cumulative inflammatory damage that contributes to cardiovascular aging, the return on that annual shot is much greater than previously appreciated.
The broader question is whether this holds for other vaccines as well. There is growing evidence that COVID vaccination offers similar cardiovascular protection after infection. And what does this mean for the development of universal flu vaccines, which researchers have been pursuing for years? If infection prevention becomes a formal pillar of aging medicine, it could fundamentally change how we think about preventive care in later life.