Shingrix linked to fewer heart events than Zostavax over seven years

A switch in U.S. shingles vaccines has given researchers a rare health experiment. After the move from the live attenuated Zostavax to the recombinant Shingrix in October 2017, adults aged 60 and older who received Shingrix showed fewer cardiovascular events over the following seven years than otherwise similar Zostavax recipients.

Researchers at the University of Oxford and NIHR BRC: Oxford Health used the U.S. TriNetX electronic health records network, matching more than 36,000 people in each group. That design avoids one major problem in earlier studies: comparing vaccinated people with unvaccinated people, who may differ in health and behavior before vaccination.

The Shingrix group had a 9% lower overall burden of cardiovascular disease than the Zostavax group. The association included a 10% reduction in ischemic heart disease, a 12% reduction in heart failure and a 7% reduction in atrial fibrillation, an irregular heart rhythm. Among men, stroke risk was 12% lower. The association appeared in both sexes and was strongest in the years soon after vaccination.

For older adults, the immediate practical change is limited but concrete: Shingrix is already the current shingles vaccine in the United States and is offered through the NHS to older people and certain other groups in the U.K. The findings add a possible heart benefit to its established purpose of preventing shingles, but they do not yet support taking the vaccine specifically to prevent cardiovascular disease.

The uncertainty is about both cause and mechanism. The researchers say randomized clinical trials are still needed to establish that Shingrix itself protects the heart. One possibility is that preventing herpes zoster infection lowers cardiovascular risk; another is that chemicals in the vaccine may have separate effects. The present result is an association, not proof of either explanation.