This common vaccine cuts heart risk nearly in half in new study

Key Findings Unveiled at ACC.26

The comprehensive study, drawing data from a vast cohort of over 246,822 adults across the United States, focused on individuals diagnosed with atherosclerotic heart disease – a prevalent and serious condition characterized by plaque buildup within the arteries. The research revealed a remarkable reduction in major adverse cardiac events (MACE) among vaccinated individuals. Specifically, those who had received at least one dose of the shingles vaccine were 46% less likely to experience a MACE within a year. Furthermore, the vaccine was associated with a 66% lower risk of all-cause mortality, a staggering figure that highlights its potential to significantly extend lives in this vulnerable population.

Delving deeper into specific cardiovascular outcomes, the study showed that vaccinated patients experienced a 32% reduction in the risk of heart attack (myocardial infarction), a 25% decrease in the risk of stroke, and a 25% lower risk of heart failure. These percentages represent substantial clinical benefits, offering a new dimension to preventive strategies for individuals already grappling with the complexities of heart disease. Dr. Robert Nguyen, a resident physician at the University of California, Riverside, and the lead author of the study, emphasized the profound nature of these reductions. "This vaccine has been found over and over again to have cardioprotective effects for reducing heart attack, stroke and death," Dr. Nguyen stated. "Looking at the highest risk population, those with existing cardiovascular disease, these protective effects might be even greater than among the general public." His remarks underscore the importance of targeting high-risk groups for vaccination, where the benefits appear particularly pronounced.

Understanding Atherosclerotic Heart Disease and Its Global Burden

Atherosclerotic heart disease (ASHD) is the leading cause of morbidity and mortality worldwide. It encompasses conditions such as coronary artery disease, peripheral artery disease, and cerebrovascular disease, all stemming from the gradual accumulation of fatty plaques within arterial walls. This process can narrow arteries, restrict blood flow, and lead to serious events like heart attacks and strokes. According to the World Health Organization (WHO), cardiovascular diseases (CVDs) are the number one cause of death globally, claiming an estimated 17.9 million lives each year. In the United States alone, approximately 18.2 million adults aged 20 and older have coronary artery disease, the most common type of heart disease, highlighting the immense public health challenge that ASHD presents. For individuals already diagnosed with ASHD, managing risk factors and preventing recurrent events is paramount. The new findings suggest that the shingles vaccine could become a crucial, yet previously overlooked, component of this secondary prevention strategy.

Methodology: A Large-Scale Real-World Data Analysis

To conduct this robust analysis, researchers leveraged TriNetX, an extensive federated research network that aggregates de-identified electronic medical records from millions of Americans across numerous healthcare organizations. This powerful database allowed for the examination of real-world patient outcomes on an unprecedented scale. The study focused on adults aged 50 years or older with an existing diagnosis of atherosclerotic disease, tracking data collected between 2018 and 2025.

The research team carefully constructed two cohorts: 123,411 individuals who had received at least one dose of either the Shingrix or Zostavax vaccine (the two primary shingles vaccines available) and an equally sized control group of 123,411 unvaccinated individuals. Crucially, both groups were meticulously matched based on a wide array of demographic characteristics (such as age, sex, race, and ethnicity) and pre-existing health conditions (comorbidities like diabetes, hypertension, hyperlipidemia, and smoking status). This rigorous matching process was designed to minimize confounding factors and ensure that any observed differences in outcomes could be more confidently attributed to the vaccination status rather than underlying health disparities.

The researchers then meticulously tracked heart-related outcomes that occurred between one month and one year following vaccination (or within the equivalent timeframe for the unvaccinated control group). This specific window was chosen to allow sufficient time for the vaccine to elicit an immune response while also capturing acute and subacute cardiovascular events potentially influenced by the vaccine’s protective effects.

The Shingles-Cardiovascular Link: A Deeper Dive into Mechanisms

The Centers for Disease Control and Prevention (CDC) recommends the shingles vaccine for adults aged 50 years and older, as well as for younger individuals with compromised immune systems. Shingles, or herpes zoster, is a painful viral infection characterized by a blistering rash, which can lead to debilitating, long-lasting nerve pain known as post-herpetic neuralgia (PHN). It arises from the reactivation of the varicella-zoster virus (VZV), the same virus responsible for chickenpox, which lies dormant in nerve cells for decades after the initial childhood infection.

The connection between shingles and an increased risk of cardiovascular events has been a growing area of research interest. Earlier studies have illuminated a plausible biological pathway: a shingles infection is not merely a localized skin condition but can trigger systemic inflammation. This widespread inflammatory response, coupled with direct viral effects on blood vessels, can lead to endothelial dysfunction (damage to the inner lining of blood vessels), increase oxidative stress, and promote a pro-thrombotic state. Essentially, the body’s response to the reactivated VZV can create an environment conducive to blood clot formation, particularly near vital organs like the brain and heart. This heightened thrombotic risk, along with potential vasculitis (inflammation of blood vessels), can significantly elevate the likelihood of acute cardiovascular events such such as heart attacks, strokes, and venous thromboembolism. By preventing the shingles infection, the vaccine is hypothesized to interrupt this dangerous inflammatory cascade, thereby mitigating the associated cardiovascular risks.

A History of Vaccine Development and Public Health Impact

The development of shingles vaccines represents a significant public health achievement. Zostavax, a live-attenuated vaccine, was approved in 2006. While effective, its efficacy waned over time and was not recommended for immunocompromised individuals. Shingrix, a recombinant subunit vaccine, received FDA approval in 2017. It demonstrated superior efficacy (over 90% in adults 50 and older) and a longer duration of protection, quickly becoming the preferred vaccine. The CDC’s Advisory Committee on Immunization Practices (ACIP) updated its recommendations to favor Shingrix, administered in two doses. This strategic shift in vaccination guidelines has been instrumental in broadening protection against shingles and, as this new research suggests, potentially against severe cardiovascular outcomes.

The impact of vaccines on global health cannot be overstated. From eradicating smallpox to significantly reducing the incidence of polio, measles, and influenza, vaccines stand as one of the most cost-effective and powerful tools in preventive medicine. The notion that a vaccine primarily designed for one disease (shingles) could offer substantial protection against another major health threat (heart disease) further reinforces the multifaceted benefits of robust vaccination programs.

Broader Implications for Public Health and Clinical Practice

The findings presented at ACC.26 carry profound implications for both public health policy and individual clinical practice. For public health authorities, these results provide compelling additional evidence to reinforce existing recommendations for shingles vaccination, particularly in older adults and those with underlying health conditions. Highlighting the cardioprotective effects could serve as a powerful motivator for increasing vaccine uptake rates, which, despite CDC recommendations, still fall short of optimal levels.

For cardiologists, primary care physicians, and other healthcare providers, this research offers a new talking point in patient counseling. When discussing cardiovascular risk reduction strategies, physicians can now explicitly include shingles vaccination as a potentially vital component. This is particularly relevant for patients with existing atherosclerotic heart disease, where every percentage point reduction in risk can translate into saved lives and improved quality of life. Dr. Nguyen reinforced this perspective, noting, "Vaccines are one of the most important medicines we have to prevent disease. Sometimes patients are unsure about whether they should get a vaccine or not, particularly in an age of disinformation. These results provide another reason for them to elect to get the vaccine." In an era marked by vaccine hesitancy and the proliferation of misinformation, such robust, real-world data can serve as a critical counter-narrative, empowering patients and providers alike.

The economic implications are also significant. Cardiovascular disease places an enormous burden on healthcare systems globally, with direct and indirect costs running into hundreds of billions of dollars annually. A vaccine that can substantially reduce the incidence of heart attacks, strokes, and heart failure in a high-risk population could lead to considerable healthcare savings by preventing costly hospitalizations, rehabilitation, and long-term care needs.

Limitations and Future Research Directions

While the study presents robust and highly encouraging findings, it is important to acknowledge its limitations. The analysis primarily tracked outcomes during the first year after vaccination. While this period captures acute and subacute events, the long-term effects of shingles vaccination on cardiovascular health warrant further investigation. However, prior research, including a study published recently, has already hinted at sustained benefits, linking shingles vaccination to a 23% reduction in cardiovascular events in generally healthy adults, with protective effects potentially lasting up to eight years. This suggests that the benefits observed in the current study may extend well beyond the initial year.

Another inherent limitation in observational studies of this nature is the potential for "healthy user bias." Individuals who choose to get vaccinated may, on average, also engage in other healthier behaviors, such as adhering to medication regimens, eating a balanced diet, and exercising regularly. While the researchers made considerable efforts to adjust for a wide range of health and socioeconomic factors (including issues related to housing, economic circumstances, social environment, employment status, education, and literacy), it remains a possibility that some residual confounding by unmeasured lifestyle differences could influence the observed benefit. Despite this, the study’s exceptionally large sample size and sophisticated statistical matching techniques provide strong evidence that shingles vaccination is independently associated with a meaningful and clinically significant reduction in heart disease risk.

Looking ahead, future research will likely focus on several key areas. Longer-term follow-up studies are crucial to ascertain the durability of the cardioprotective effects. Mechanistic studies could further elucidate the precise molecular and cellular pathways through which shingles infection impacts cardiovascular health and how the vaccine modulates these processes. Furthermore, cost-effectiveness analyses will be vital to inform public health policy decisions and optimize resource allocation.

The presentation of this pivotal research, titled "Herpes Zoster Vaccination and Risk of Cardiovascular Events in Patients with Atherosclerotic Cardiovascular Disease," is scheduled for Monday, March 30, at 12:30 p.m. CT / 17:30 UTC in Posters, Hall E, at the American College of Cardiology’s Annual Scientific Session. Its findings are poised to significantly influence discussions around comprehensive cardiovascular disease prevention and the broader role of vaccination in promoting overall health.