A common shingles vaccine, studied in more than 70,000 adults aged 60 and older in the United States, is associated with a reduction of about 9% of the burden of major cardiovascular diseases over seven years, according to a team from the University of Oxford. Researchers describe a reduction in diagnoses of coronary heart disease,heart failure and, among men,cerebrovascular accident (CVA)compared to the old vaccine used against shingles.
This vaccine, Shingrixis a recombinant vaccine now recommended in many countries, including the United Kingdom, in place of the live attenuated vaccine
Zostavax. The authors show that Shingrix is linked to a 10% reduction in coronary heart disease and a 12% reduction in heart failure, with a greater effect in the first years after the injection. For the reader, this does not transform the shingles vaccine into a “heart treatment”, but suggests a possible cardiovascular bonus in those over 60 already eligible for vaccination.
Shingrix: a shingles vaccine that also seems to protect the heart
The researchers used electronic medical records from the TriNetX US Collaborative Networkcovering approximately 60 healthcare organizations. Two cohorts of 36,460 people were compared: those vaccinated in April-September 2017, when 98.6% were still receiving Zostavax, and those vaccinated a year later, a period when 93.5% received Shingrix. When analyzed, Shingrix was associated with a 9% reduction in the overall incidence of cardiovascular disease compared to Zostavax, including a 10% reduction in ischemic heart disease and a 12% reduction in heart failure.
Shingrix is also associated with a 7% reduction in atrial fibrillation. On the other hand, ischemic stroke is not significantly reduced when looking at all patients, even though men vaccinated with Shingrix have a 12% lower risk of stroke. An analysis specifies that the reduction in cardiovascular events reaches around 12% during the three and a half years following vaccination, then attenuates to around 4% after seven years.
A more robust natural experiment than “vaccinated vs unvaccinated”
Unlike previous studies which pitted vaccinated and unvaccinated people against each other, this team from the University of Oxford took advantage of the abrupt “switch” between vaccines. For researcher Fabiana Corsi‑Zuelli, “Because we used a natural experiment created by rapid switching from one vaccine to another, our study addresses many of the biases of traditional cohorts. But a randomized clinical trial is needed to confirm that the vaccine actually protects the heart“.
Maxime Taquet recalls another intriguing result: “Having already shown that this vaccine is linked to a lower risk of dementia, we now see that it could also protect the heart. If confirmed in clinical trials, vaccinating older people against shingles could prevent hundreds of thousands of coronary heart disease, strokes and cases of heart failure worldwide, making it one of the most impactful interventions to protect both the brain and heart as we age.“.
Real effect or coincidence? What the experts think
Psychiatrist Paul Harrison reminds us that the exact biology remains mysterious: “A key question is how the vaccine produces its apparent protective effect on the heart. One possibility is that infection with the shingles virus increases the risk of cardiovascular disease and therefore, by inhibiting the virus, the vaccine may reduce this risk. It is also possible that the vaccine contains chemicals that could have distinct beneficial effects on the heart“. Work suggests, for example, that the adjuvant AS01 could attenuate certain inflammatory responses, such as interleukin-6.
Outside experts, such as Hugo Pedder at the University of Bristol, remain cautious: “A randomized trial would be the best way to definitively answer the question of whether recombinant vaccines provide the benefits observed here over live vaccines, but until such a trial is performed, this study provides some of the highest quality observational evidence supporting an effect of recombinant vaccines over live vaccines on cardiovascular outcomes“. For the moment, these results mainly reinforce the interest of Shingrix among the over 60s already targeted to protect themselves from shingles.