Tejal Somvanshi
Two significant research findings released this week suggest that a newer dementia-risk-by-20-in-seniors-over-7-years/”>shingles vaccine may protect against cardiovascular disease and dementia in older adults, though researchers caution these findings show association rather than definitive proof.
A study published today in *Nature Medicine* analyzed a natural experiment in the United States: the rapid switch from an older live vaccine to a newer recombinant version. The recombinant shingles vaccine—which uses genetically engineered viral proteins rather than a weakened live virus—showed a 9 percent decrease in cardiovascular events over seven years among adults 60 and older. This composite category includes ischemic heart disease, heart failure, and ischemic stroke. The reductions were more pronounced for specific conditions: ischemic heart disease dropped by 10 percent, and heart failure by 12 percent in both men and women. Men also saw a 12 percent reduction in ischemic stroke. Atrial fibrillation, an irregular heartbeat condition, fell by 7 percent.
The researchers examined 36,460 propensity-matched adults in each vaccine group using data from the TriNetX US Network, which comprises over 100 million medical records across roughly 60 healthcare organizations. The timing allowed for a particularly clean comparison: between April and September 2017, 98.6 percent of vaccinated Americans received the older live attenuated vaccine. Within one year, 93.5 percent had switched to the recombinant version.
The live vaccine, called Zostavax, was discontinued in the United States in 2020. The newer recombinant vaccine, Shingrix, is manufactured by GSK.
Separately, a Brown University study published in the *Annals of Internal Medicine* found that older adults who received at least one dose of the recombinant shingles vaccine had a 24 percent lower risk of developing dementia over four years compared to unvaccinated adults. The research included 509,926 Americans aged 66 and older living in skilled nursing facilities.
“The finding is remarkable,” said Dr. Ajeet Sodhi, a neurologist in Orlando quoted in reporting on the dementia study. However, he emphasized an important distinction: the vaccine’s association with lower dementia risk “is not proof the vaccine prevents dementia.”
That caveat applies to both studies. These are observational findings based on comparing groups of people—they show correlation, not causation. To establish whether the vaccine actually causes these protective effects, controlled clinical trials would be necessary.
The biological mechanism remains speculative but plausible. Shingles is caused by the varicella-zoster virus, which is the same virus responsible for chickenpox. In people with past chickenpox infection, the virus can reactivate decades later, causing shingles. Researchers hypothesize that the varicella-zoster virus may contribute to inflammation in blood vessels and the brain, which could increase risk for heart disease and dementia. A more effective vaccine might reduce this inflammation.
The cardiovascular study’s authors call for future clinical trials and mechanistic research to understand how the recombinant vaccine might protect the heart and brain. Such targeted investigations could help clarify whether these observed associations reflect a genuine protective effect or result from differences between vaccinated and unvaccinated populations.
For now, these findings add to a growing body of evidence suggesting that the recombinant shingles vaccine offers benefits beyond preventing shingles itself. The Centers for Disease Control and Prevention already recommends the vaccine for all adults 50 and older. The new associations with cardiovascular and cognitive health outcomes may strengthen the case for vaccination in older populations.
