A recent observational analysis published in Nature Medicine compared cardiovascular outcomes in adults aged 60 and older who received either the recombinant zoster vaccine Shingrix or the live-virus vaccine Zostavax. Using data from the USA TriNetX electronic health records network, investigators identified 72,920 people: 36,460 who had received Shingrix and an equal number who had received Zostavax.
Over a seven-year follow-up period, the researchers report a 9% reduction in cardiovascular burden among people who received Shingrix compared with those who received Zostavax. The study adds to prior observational work suggesting that the recombinant zoster vaccine may have benefits beyond shingles prevention.
The authors and quoted study investigators highlighted the potential public health importance of even modest relative reductions in cardiovascular disease, given that cardiovascular conditions remain the leading cause of death globally.
Beyond the primary composite measure of cardiovascular burden, the analysis identified several condition-specific associations. Compared with Zostavax recipients, people who received Shingrix had a reported 10% lower burden of ischemic heart disease and a 12% lower burden of heart failure over seven years.
Sex-specific findings included a 12% reduction in stroke burden among men who received Shingrix. Both men and women vaccinated with Shingrix showed a 7% lower burden of atrial fibrillation in the follow-up period.
Investigators described these findings as potentially clinically meaningful, particularly because strokes and heart failure are associated with high morbidity and mortality. However, they also stressed that the study design does not establish causation.
Clinicians and researchers interviewed in the article proposed two broad, non–mutually exclusive explanations for the observed associations. One explanation is indirect: preventing shingles may reduce episodes of infection-related inflammation that have been linked previously with increased cardiovascular risk. Shingles can provoke significant inflammatory responses that may transiently increase risk for cardiovascular events; preventing the infection could therefore reduce that downstream risk.
A second hypothesis involves the vaccine platform itself. Shingrix contains an adjuvant, AS01, that enhances immune responses to the recombinant antigen. Experts suggested the adjuvant-driven immune stimulation might induce longer-lasting changes in immune cell function or inflammatory signaling pathways. The study highlights interleukin-6 (IL-6) as one inflammatory mediator of interest that has been associated with cardiovascular disease; modulation of such pathways by the vaccine could conceivably contribute to sustained cardiovascular protection.
These mechanistic ideas remain hypothetical. The article notes that experimental and mechanistic studies are needed to determine whether and how Shingrix might directly influence immune or vascular inflammation to lower cardiovascular risk.
Commentators emphasized the broader implications if the associations are causal. Given the large global burden of cardiovascular disease, an intervention that reduces cardiovascular events even modestly could yield significant public health benefits. Several clinicians quoted in the piece described the findings as intriguing and encouraging, noting that vaccines are among the most effective public health tools and that benefits beyond prevention of the target infection would be important.
At the same time, experts repeatedly cautioned that the study is observational. The authors stated that randomized clinical trials are necessary to confirm causality. The article reports that two randomized trials are underway, and that further mechanistic and age-stratified work is required to clarify when any additional benefits are most likely to occur.
The recombinant zoster vaccine Shingrix was approved by the U.S. Food and Drug Administration in 2017, and the Centers for Disease Control and Prevention recommends two doses for adults aged 50 and older to prevent shingles. Prior observational studies have also suggested links between Shingrix and lower risks of dementia and cardiovascular disease; this new analysis adds further observational evidence of a potential cardiovascular benefit.
Clinicians in the article noted that Shingrix already reduces the incidence and complications of shingles, which alone is a compelling reason to vaccinate eligible adults. If randomized trials confirm a causal reduction in cardiovascular events, that would provide an additional rationale to promote vaccination. Until then, the findings should be interpreted cautiously: promising but not proof of a direct protective effect.