The Shingles Vaccine Cuts Heart Attack Risk Nearly as Much as Quitting Smoking

Consider who fills the cardiac ward. Patients with atherosclerotic heart disease, arteries narrowed by decades of accumulated plaque, already taking statins and beta-blockers and aspirin, already doing roughly everything that medicine asks of them. The idea that a vaccine against a blistering nerve rash could meaningfully reduce their chances of a heart attack, a stroke, or an early death might seem, at first pass, a bit far-fetched. But a large new study being presented at the American College of Cardiology’s annual meeting this week suggests it can, and the magnitude of the effect is striking enough that some cardiologists are now wondering whether the humble shingles jab has been doing something quietly remarkable all along.

The research, led by Robert Nguyen at the University of California, Riverside, drew on health records from TriNetX, a database covering millions of Americans. Working with over 246,000 adults aged 50 and older who already had atherosclerotic cardiovascular disease, Nguyen’s team matched 123,411 people who had received at least one dose of a shingles vaccine with the same number who had not, balancing the groups for age, sex, and a range of other health and socioeconomic factors. They then looked at what happened in the year that followed.

The numbers that came back were, by any measure, substantial. Vaccinated individuals were 46 percent less likely to suffer a major adverse cardiac event than their unvaccinated counterparts. They were 32 percent less likely to have a heart attack, 25 percent less likely to have a stroke, 25 percent less likely to develop heart failure, and fully 66 percent less likely to die from any cause. Nguyen himself reached for one of medicine’s most familiar benchmarks to put the scale of the benefit in context: these levels of risk reduction are comparable, he said, to what you’d expect from quitting smoking.

That comparison lands hard. Smoking cessation is probably the single most impactful lifestyle change a cardiac patient can make. The shingles vaccine, by contrast, is a two-dose course that most adults over 50 can get at a pharmacy.

So what is it actually doing? The leading hypothesis involves clotting. When herpes zoster, the virus responsible for shingles, reactivates in the body (as it tends to do, often decades after the original chickenpox infection, when immunity starts to wane), it can trigger the formation of blood clots in and around the vasculature supplying the brain and heart. In someone whose arteries are already narrowed by atherosclerosis, a clot of that sort doesn’t need to be particularly large to cause serious damage. By preventing the infection in the first place, the vaccine may be cutting off this clotting cascade before it starts.

“Looking at the highest risk population, those with existing cardiovascular disease, these protective effects might be even greater than among the general public,” Nguyen said. It’s perhaps an intuitive idea in hindsight. If your cardiovascular system is already under strain, adding a clot-triggering viral infection to the mix is arguably the worst possible timing.

This isn’t the first study to suggest the vaccine does something beyond its stated job description. A paper published in 2025 found that in a general, broadly healthy population, shingles vaccination was associated with a 23 percent lower risk of cardiovascular events, with protective effects apparently lasting up to eight years. What the new study adds is specificity about the highest-risk group, the people for whom every percentage point of risk reduction matters most.

There are, naturally, reasons to be cautious. The study is observational rather than randomised, which means it cannot definitively rule out that people who seek out vaccination are also, in various hard-to-measure ways, healthier or more health-conscious than those who don’t. The researchers controlled for housing instability, employment, education, and a range of other socioeconomic factors, but the so-called “healthy vaccinee” bias is notoriously difficult to fully eliminate from studies like this one. Nguyen acknowledges the limitation, though he argues the study’s size and statistical rigour still support a high degree of confidence.

The findings also only capture outcomes during the first year after vaccination. Whether the benefits continue, plateau, or diminish after that point remains, for now, an open question.

None of this stops the study from having immediate practical relevance. The Centers for Disease Control and Prevention already recommends the shingles vaccine for all adults 50 and over, a recommendation that existed purely on the basis of preventing shingles itself. If the cardiac data continues to hold up under scrutiny, it provides a second, arguably more urgent, justification to get vaccinated, particularly for patients who have already had a cardiac event and may be weighing the risk-benefit calculation carefully.

Medicine occasionally turns up these unexpected bonuses: a drug or intervention approved for one purpose quietly turning out to protect against something else entirely. In an era of widespread vaccine hesitancy, a finding of this sort carries a particular kind of weight. Not because it should be deployed as a rhetorical trump card, but because it represents a genuine expansion of what this vaccine appears to be doing inside the body. The biology of protection, it turns out, doesn’t always stop at the organ it was designed to defend.

Frequently Asked Questions