Shingles develops when the varicella-zoster virus, which remains in the body after chickenpox, reactivates. The disease is often accompanied by severe pain and is particularly dangerous for older adults, which is why vaccination is recommended for them in many countries. The recombinant shingles vaccine may not only prevent disease caused by reactivation of the varicella-zoster virus but also reduce the risk of cardiovascular events.
Previous studies have suggested a lower risk of cardiovascular disease after recombinant vaccine administration. However, they compared vaccinated and unvaccinated people, making their findings difficult to interpret unambiguously: vaccinated people may, on average, take better care of their health and differ from unvaccinated individuals in other important characteristics.
In the new study, scientists from the University of Oxford compared people who received different types of shingles vaccines. After October 2017, the live vaccine was rapidly replaced by the recombinant vaccine, creating an opportunity to compare cardiovascular outcomes in people who received the different vaccine types.
This natural experiment made it possible to more reliably assess whether the presumed reduction in cardiovascular risk was specifically associated with the recombinant vaccine rather than with characteristics of people who choose to get vaccinated.
Study Methods and Results
The scientists compared data from about 73,000 people over age 60 who were vaccinated against shingles in 2017 and 2018. In 2017, approximately 99% of participants received the live vaccine (control group), whereas in 2018, nearly 94% received the recombinant vaccine. The two groups had similar numbers of participants.
Over the following seven years, people who predominantly received the recombinant vaccine had 9% longer event-free survival without coronary artery disease, ischemic stroke, or heart failure than those in the control group. They also had a lower incidence of atrial fibrillation, while men additionally had a reduced risk of ischemic stroke. The association was observed in both sexes, was strongest during the first half of the follow-up period, and weakened over time.
Vaccination did not affect the risk of myocarditis, peripheral artery disease, hemorrhagic stroke, or transient ischemic attack.
Possible Protective Mechanism
The recombinant vaccine may induce immune and endothelial changes that have cardioprotective effects. The AS01 adjuvant used in the recombinant vaccine causes long-lasting changes in monocyte function. In particular, monocytes begin to produce less of the pro-inflammatory protein IL-6 in response to Toll-like receptor activation. Reduced IL-6 activity, in turn, is associated with a lower risk of cardiovascular disease.
This effect may weaken over time, aligning with the study findings: the association between vaccination and reduced cardiovascular risk was strongest during the first half of the seven-year follow-up period and then weakened.
Conclusion
If clinical trials confirm that the recombinant shingles vaccine truly reduces cardiovascular risk, a 0.8% reduction in the incidence of coronary artery disease and heart failure among people over the age of 60 could prevent hundreds of thousands of cases of these diseases.
Reference
Recombinant shingles vaccination and the risk of cardiovascular events
