Researchers at the University of Oxford found that adults receiving the Shingrix shingles vaccine experienced a roughly 12 percent lower risk of major cardiovascular events, including heart attacks and strokes, during the following three and a half years, according to a study published in Nature Medicine.
The research examined electronic health records from about 70,000 U.S. adults aged 60 and older to track major health outcomes after vaccination (The Guardian). Rather than simply comparing vaccinated people with unvaccinated individuals—a method that can distort results because health-conscious people often choose to get vaccinated—the study leveraged a natural experiment (STAT). Investigators analyzed matched patient groups on either side of October 2017, the period when the U.S. rapidly transitioned from the older live-virus vaccine, Zostavax, to the newer recombinant vaccine, Shingrix (Nature).
Natural Experiment Design Isolates Vaccine Impact
Previous observational studies hinted that vaccinated individuals faced lower rates of cardiovascular disease, but researchers continually questioned whether healthier lifestyle choices or better healthcare access among vaccine recipients explained the difference (STAT). The Oxford-led team sought to answer that what else could it be?
dilemma by evaluating records from the TriNetX network, which covers approximately 60 healthcare organizations and more than 100 million patients (Nature).
By comparing patients who received their inoculations just before or just after the 2017 transition, the study achieved well-balanced cohorts (STAT). Compliance with the instrument was very high: 98.6 percent of individuals in the April–September 2017 cohort received the live vaccine, while 93.5 percent of those in the April–September 2018 cohort received the recombinant vaccine (Nature). This natural shift effectively bypassed healthy vaccine bias (STAT).
Cardiovascular Reduction and Absolute Risk Realities
Over the initial three and a half years of follow-up, patients given Shingrix exhibited a 12% lower risk of a cardiovascular diagnosis (The Guardian). Looking across a seven-year span, receiving Shingrix rather than Zostavax was associated with a 9 percent lower overall cardiovascular burden, which encompassed coronary heart disease, heart failure, and stroke (STAT). Specifically, coronary heart disease dropped by 10 percent, heart failure fell by 12 percent, and atrial fibrillation decreased by 7 percent (STAT). Strokes were down 12 percent in men, though the reduction was not statistically significant among women (STAT).
While the relative risk reduction sounds substantial, experts emphasize that the absolute risk change is considerably smaller (Nchstats). Cardiovascular events occurred in only a portion of the study population, translating in absolute terms to roughly 1 percent fewer cardiovascular events after seven years (STAT). Nevertheless, because millions of older adults receive shingles inoculations, even a modest individual change can prevent a massive number of events at a population level (STAT).
“If confirmed in clinical trials, vaccinating older adults against shingles could prevent hundreds of thousands of coronary heart diseases, strokes and cases of heart failure worldwide, making it one of the most impactful interventions we could offer to protect both the brain and the heart in later life. The effect might be enormous.”
Dr Maxime Taquet, a clinical lecturer at the University of Oxford
Exploring Mechanisms and Broader Health Debates
The exact biological mechanism connecting the recombinant vaccine to heart protection remains unproven (STAT). Researchers point out that the varicella-zoster virus—the pathogen responsible for both chickenpox and shingles—is known to heighten cardiovascular and vascular disease risks following reactivation (The Guardian), meaning superior viral suppression could protect blood vessels (STAT). Alternatively, scientists hypothesize that the vaccine might induce trained immunity,
causing beneficial, long-lasting functional changes in innate immune cells (STAT).
These findings arrive amid broader scientific discussions regarding whether Shingrix provides neuroprotective benefits against dementia (Nchstats). While some large-scale analyses have suggested lower dementia rates or reduced mortality among patients with existing diagnoses (Nchstats), other major studies—such as an Oxford analysis of over 6.3 million patient records—found little evidence that eligibility for older shingles vaccines reduced hospital-recorded dementia (Nchstats).
Because the current cardiovascular study remains observational, independent researchers stress the need for randomized controlled trials (The Guardian). A definitive answer may arrive soon, as the DAN ZOSTER trial involving roughly 162,000 participants in Denmark moves toward its initial results anticipated in 2027 (STAT).
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