In a paper published yesterday in Nature Medicine, University of Oxford researchers conclude that the recombinant herpes zoster (shingles) vaccine could lower the likelihood of cardiovascular disease better than the live attenuated vaccine, which was discontinued in the United States in 2020 because of its lower efficacy and rapid waning.
Shingles causes a blistering, painful rash and can contribute to lingering complications such as nerve damage, hearing and vision loss, and encephalitis (inflammation of the brain). Past research has also suggested that it can cause blood clots around the brain and heart, which can lead to heart attack, stroke, and blood clots in the veins.
Protection for various heart-related conditions ranged from 7% to 12%.
Health agencies recommend the shingles vaccine (Shingrix) for adults aged 50 and older.
“Receiving the recombinant shingles vaccine is associated with a reduced risk of cardiovascular events compared to the live attenuated vaccine,” the authors wrote. “Given the global burden of cardiovascular disease, these findings, if confirmed in clinical trials and mechanistic studies, would have important implications for public health.”
Mechanisms behind the benefit still unclear
After the recombinant vaccine replaced the live attenuated version, the scientists conducted a natural experiment using the electronic health records of two groups of vaccinated adults older than 60 years.
The first cohort included 36,460 recipients of a live attenuated shingles vaccine from April to September 2017. The second group, which was the same size, received the recombinant vaccine from April to September 2018.
Receiving the recombinant shingles vaccine is associated with a reduced risk of cardiovascular events compared to the live attenuated vaccine.
For the next seven years, those who received the recombinant vaccine were less likely to die or experience cardiovascular events such as ischemic heart disease (10% reduction), heart failure (12%), and atrial fibrillation (7%) than those who got the discontinued version. Men who received that shingles vaccine also had a 12% lower chance of ischemic stroke.
The researchers chose to compare recipients of different vaccines to try to avoid the “healthy vaccinee bias,” which can occur when studies compare people who received a vaccine to those who did not. People who are regularly vaccinated tend to be healthier than those who aren’t, so this study design eliminated this bias.
“The biological mechanisms underlying these observations remain to be clarified experimentally,” the authors wrote. “A more plausible explanation is that the recombinant vaccine may induce immune and endothelial changes that could be cardioprotective.”
