New Shingles Vaccine Linked to Significant Drop in Stroke and Heart Failure Risk

Introduction

A groundbreaking study involving over 72,000 individuals suggests that receiving the latest shingles vaccine, Shingrix, could offer significant protection against serious cardiovascular events such as stroke and heart failure. This finding emerges from a comparison between recipients of Shingrix and those who received an older shingles vaccine, Zostavax, providing a more robust understanding of vaccine-induced cardiovascular benefits.

Key Details

• The study analyzed medical records of over 72,000 people aged 60 and older.
• Participants were divided into two groups: those who received the older Zostavax vaccine before October 2017 and those who received the newer Shingrix vaccine afterward.
• Over a 3.5-year follow-up period, 10.9% of Zostavax recipients developed heart failure, stroke, or clogged arteries, compared to 9.6% of Shingrix recipients.
• This represents a statistically significant reduction in cardiovascular events associated with the Shingrix vaccine.
• The benefit, while diminishing over time, remained higher in the Shingrix group.

Background

Shingles, a painful condition caused by the reactivation of the varicella-zoster virus (the same virus that causes chickenpox), affects a substantial portion of the population. While primarily known for its distressing rash, shingles can also lead to complications. Previous research had hinted at a link between shingles vaccination and reduced cardiovascular risk, but these studies often compared vaccinated individuals to unvaccinated ones. This comparison is prone to bias, as individuals who opt for vaccination may also lead healthier lifestyles overall, making it difficult to isolate the vaccine's specific effect.

To overcome these limitations, researchers, led by Max Taquet at the University of Oxford, utilized a unique opportunity. In October 2017, the standard shingles vaccine in the US transitioned from Zostavax to Shingrix. Zostavax uses a live, attenuated virus, whereas Shingrix is composed of a viral protein combined with a potent immune-stimulating adjuvant called AS01. This change in vaccine formulation provided a natural experiment, allowing researchers to compare the cardiovascular outcomes of individuals who received the older vaccine shortly before the switch with those who received the newer one shortly after.

“People should get their shingles vaccine not only because it stops them getting shingles, which in [and] of itself can be very unpleasant and quite dangerous, but also it potentially gives you protection against dementia and heart disease,” says John Tregoning at Imperial College London, who wasn’t involved in the study.

Impact Analysis

The study's findings indicate that the Shingrix vaccine is associated with approximately a 13% relative reduction in the risk of developing heart failure, stroke, or clogged arteries compared to Zostavax. While the percentage difference may seem small, the sheer number of people affected by cardiovascular disease means this translates into a substantial number of preventable cases. “Even though the percentage changes are small, the absolute numbers of heart disease cases are high, so it can lead to a large actual number of people being protected,” noted John Tregoning.

The mechanism behind this cardiovascular protection is not fully understood but is hypothesized to involve the AS01 adjuvant in Shingrix. Betty Raman, also from the University of Oxford, explained that AS01 may reprogram immune cells, specifically monocytes, to produce fewer inflammatory molecules known as cytokines. Chronic inflammation is a known contributor to the development of atherosclerosis, the hardening and narrowing of arteries, which underlies many cardiovascular diseases. By potentially dampening this inflammatory response, Shingrix might offer a protective effect on the cardiovascular system.

Broader Context

The implications of this research are significant, especially considering the widespread eligibility for shingles vaccination. In the US, the eligibility age for the shingles vaccine was lowered to 50 in October 2017, coinciding with Shingrix's introduction. Researchers estimate that if all eligible individuals in the US were to receive Shingrix, it could prevent or delay hundreds of thousands of cardiovascular events within a decade. Currently, vaccine uptake remains relatively low, with only about a third of eligible individuals receiving the shot. In the UK, the vaccine is offered to those turning 65 or older starting from September 2023.

Furthermore, Shingrix has demonstrated superior efficacy in preventing shingles itself compared to Zostavax. Preventing shingles infections could indirectly benefit cardiovascular health, as viral infections can trigger systemic inflammation that stresses the heart and other organs.

Future Outlook

Further validation is expected from an ongoing large-scale trial in Denmark involving over 160,000 participants aged 65 and older. This trial will compare outcomes between those receiving Shingrix and a control group. Initial results are anticipated in 2027. If these results confirm the cardiovascular benefits, widespread adoption of Shingrix, potentially as a routine booster, could lead to substantial improvements in public cardiovascular health and significant reductions in healthcare costs.

Conclusion

This study provides compelling evidence that the Shingrix shingles vaccine offers more than just protection against shingles; it appears to confer a notable benefit in reducing the risk of stroke and heart failure. The findings underscore the potential of advanced vaccine technology, particularly adjuvants like AS01, to modulate immune responses in ways that benefit overall health, extending beyond the primary infectious disease target. This research strengthens the case for prioritizing shingles vaccination, not just for personal comfort and safety, but as a strategic public health measure to combat cardiovascular disease.