Shingles Vaccine Significantly Reduces Cardiovascular Events in Patients with Existing Heart Disease

People living with heart disease who received a shingles vaccine experienced nearly half the rate of serious heart-related events within a year compared with those who were not vaccinated. These compelling findings, poised to reshape preventive cardiology strategies, come from research being presented at the American College of Cardiology’s Annual Scientific Session (ACC.26), a premier global gathering for cardiovascular professionals to share the latest advancements in heart health.

The comprehensive study, drawing data from an extensive network of medical records, reviewed information from more than 246,822 adults in the United States previously diagnosed with atherosclerotic heart disease. This condition, characterized by the insidious buildup of plaque within the arteries, affects millions globally and is the leading cause of heart attacks, strokes, and peripheral artery disease. The robust results of this investigation add substantial weight to a growing body of evidence suggesting that the shingles vaccine offers benefits extending far beyond its primary role of preventing herpes zoster, potentially mitigating the risk of serious conditions such as cardiovascular disease and even neurodegenerative disorders like dementia.

"This vaccine has been found over and over again to have cardioprotective effects for reducing heart attack, stroke, and death," stated Robert Nguyen, MD, a resident physician at the University of California, Riverside, and the study’s lead author. His remarks underscore the accumulating scientific consensus on the vaccine’s broad impact. "Looking at the highest risk population, those with existing cardiovascular disease, these protective effects might be even greater than among the general public." This observation highlights the critical implications for a patient demographic already facing elevated health risks.

The Burden of Cardiovascular Disease and Shingles

Atherosclerotic heart disease remains a monumental public health challenge. According to the Centers for Disease Control and Prevention (CDC), heart disease is the leading cause of death for men, women, and most racial and ethnic groups in the United States, claiming approximately 695,000 lives in 2021 alone. Coronary artery disease, a common form of atherosclerosis, affects an estimated 20.1 million adults aged 20 and older. Patients with existing atherosclerotic disease are at a significantly heightened risk for recurrent cardiovascular events, making any intervention that can reduce this risk particularly valuable.

Concurrently, shingles, or herpes zoster, is a common viral infection caused by the reactivation of the varicella-zoster virus (VZV), the same virus responsible for chickenpox. After an initial chickenpox infection, VZV remains dormant in nerve cells and can reactivate years or decades later, typically due to age-related decline in immunity or immunocompromised states. The CDC recommends the shingles vaccine for all adults age 50 years and older, as well as younger individuals with weakened immune systems, due to the severe pain and potential complications associated with the disease. These complications include postherpetic neuralgia (PHN), a long-lasting nerve pain that can be debilitating, and, as increasingly recognized, systemic effects on the cardiovascular system. Approximately one in three people in the U.S. will develop shingles during their lifetime, with the risk increasing sharply after age 50.

Mechanism of Cardioprotection: Beyond Direct Viral Effects

The precise mechanisms by which the shingles vaccine confers cardiovascular protection are a subject of ongoing research, but several hypotheses are gaining traction. Earlier research has shown that an active shingles infection can trigger a significant inflammatory response throughout the body. This inflammation can lead to endothelial dysfunction, impairing the normal function of blood vessel linings, and can promote a prothrombotic state, increasing the likelihood of blood clot formation. These clots, when forming near vital organs, can precipitate serious events such as heart attacks, strokes, and venous thromboembolism (VTE).

By preventing shingles, the vaccine effectively preempts this systemic inflammatory cascade and the subsequent heightened risk of clotting. It’s theorized that by averting the acute illness, the vaccine prevents the transient yet dangerous surge in inflammation and coagulation factors that can destabilize existing atherosclerotic plaques or trigger new thrombotic events in vulnerable patients. This indirect protective mechanism highlights the vaccine’s role not just in preventing the rash and pain of shingles, but in safeguarding overall systemic health.

A Rigorous Study Design and Significant Findings

To execute this large-scale observational study, researchers leveraged TriNetX, a vast federated research network that aggregates de-identified electronic medical records from millions of Americans across numerous healthcare organizations. This powerful tool allowed for the analysis of a broad and diverse patient population, enhancing the generalizability of the findings. The study cohort specifically included adults aged 50 years or older with an established diagnosis of atherosclerotic disease, with data spanning from 2018 through the projected close of 2025.

The analytical approach involved comparing two meticulously matched groups: 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 equal number of unvaccinated individuals. Crucially, both groups were carefully balanced across a multitude of demographic characteristics, including age, gender, race, ethnicity, and socioeconomic factors, as well as a comprehensive list of comorbidities such as hypertension, diabetes, hyperlipidemia, and chronic kidney disease. This matching process aimed to minimize confounding variables and ensure that any observed differences in outcomes could be more confidently attributed to vaccination status.

Researchers meticulously tracked heart-related outcomes occurring between one month and one year following vaccination (or an equivalent index date for the unvaccinated cohort). The results were strikingly consistent across all measured parameters, with vaccinated individuals exhibiting a substantially lower risk profile. Specifically, they were:

• 46% less likely to experience a major adverse cardiac event (MACE), a composite endpoint typically including heart attack, stroke, or cardiovascular death.
• 66% less likely to die from any cause, a profound indicator of overall health benefit.
• Their risk of heart attack (myocardial infarction) dropped by 32%.
• The risk of stroke decreased by 25%.
• The incidence of heart failure also saw a 25% reduction.

Dr. Nguyen emphasized the magnitude of these reductions, noting that they are "substantial and comparable to the benefits seen from quitting smoking," a widely recognized and impactful lifestyle intervention for cardiovascular health. He further added that these robust findings strongly reinforce current recommendations for adults over age 50 to receive the shingles vaccine.

Broader Implications for Preventive Cardiology and Public Health

These findings carry profound implications for the field of preventive cardiology and public health initiatives. The study suggests a paradigm shift, urging clinicians and patients to consider routine vaccinations not merely as protection against specific infectious diseases but as a vital component of a holistic cardiovascular risk reduction strategy. For individuals already battling atherosclerotic heart disease, where every effort to mitigate further events is critical, the shingles vaccine emerges as a surprisingly powerful tool.

The economic impact of preventing these serious cardiovascular events cannot be overstated. Heart attacks, strokes, and heart failure lead to significant healthcare expenditures, including emergency care, hospitalizations, rehabilitation, and long-term medication. A reduction in these events, as demonstrated by the study, could translate into substantial cost savings for healthcare systems and improved quality of life for countless individuals.

"Vaccines are one of the most important medicines we have to prevent disease," Dr. Nguyen stated, articulating a fundamental truth often overshadowed by public discourse. "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." His statement underscores the importance of clear, evidence-based communication in combating vaccine hesitancy and promoting public health. Public health authorities, including the CDC and organizations like the American Heart Association (AHA), are likely to reinforce these findings, advocating for increased vaccine uptake among eligible populations, especially those with pre-existing cardiovascular conditions.

Addressing Limitations and Future Directions

While the study presents compelling evidence, it is important to acknowledge certain limitations inherent in observational research. The analysis primarily tracked outcomes during the first year after vaccination, meaning the long-term effects beyond this period may differ. However, supporting this study’s findings, a previous study published in 2025 (likely a reference to another published work or an anticipated publication) found that shingles vaccination was associated with a 23% reduction in cardiovascular events in generally healthy adults, with benefits that could potentially last up to eight years, suggesting sustained protection.

Another common limitation in observational studies is the potential for confounding by indication or "healthy user bias." This refers to the possibility that people who choose to get vaccinated may also engage in healthier behaviors overall, such as regular exercise, a balanced diet, or adherence to other medical recommendations. While the researchers made considerable efforts to adjust for a wide array of health and socioeconomic factors (including issues related to housing, economic circumstances, social environment, employment status, education, and literacy) through their meticulous matching process, it is still possible that some unmeasured confounders might subtly influence the observed benefits. Despite this, the study’s exceptionally large sample size and sophisticated statistical approach provide robust evidence that shingles vaccination is strongly associated with a meaningful and clinically significant reduction in heart risk.

Future research will likely focus on several key areas. Longer-term follow-up studies are needed to ascertain the durability of the cardiovascular protection offered by the shingles vaccine. Additionally, investigations into the precise biological pathways and biomarkers linking VZV reactivation, inflammation, and cardiovascular events could further elucidate the mechanisms of protection. Randomized controlled trials, while challenging to implement for vaccine efficacy against broad outcomes, could provide the highest level of evidence.

This groundbreaking research presented at ACC.26 reinforces the critical role of vaccination in comprehensive health management. For millions living with heart disease, the shingles vaccine now offers a compelling additional reason for protection, extending its shield not only against a painful rash but potentially against life-threatening cardiovascular events.

Dr. Nguyen will formally present the study, titled "Herpes Zoster Vaccination and Risk of Cardiovascular Events in Patients with Atherosclerotic Cardiovascular Disease," on Monday, March 30, at 12:30 p.m. CT / 17:30 UTC in the Posters, Hall E session, making these crucial findings available to the global cardiology community.