Shingles vaccine linked with lower dementia risk, study shows

The shingles vaccine, recommended for people 50 and older to fight the painful viral infection, might also decrease the chances of developing dementia, according to data presented at a medical conference Tuesday.

The study, which looked at the health records of hundreds of thousands of people across the United States, shows that those who received the shingles vaccine were 20% less likely to be diagnosed with dementia in the five years following vaccination compared with a control group of people who received a vaccine for a different illness.

Pharmaceutical giant GSK, which makes the Shingrix vaccine, funded and performed the research, and presented it at the Alzheimer’s Association International Conference in Philadelphia.

Vaccine experts who were not involved in the research said that more definitive studies still need to be done, but they noted the study adds to growing recognition that infectious agents may play a role in the development of some types of dementia.

“I think this is something that we have to take seriously,” said Peter Hotez, a physician and co-director of the Texas Children’s Hospital Center for Vaccine Development.

The GSK research follows two other large studies, which were not funded by the industry, that also show a lower risk for dementia among those who were vaccinated against shingles.

Last week, researchers in the United Kingdom published a study in Nature Medicine looking at medical records of hundreds of thousands of people over six years and found that those who received Shingrix were 23% to 27% less likely to develop dementia compared with people who received vaccines against other diseases. That research was not funded by GSK, but one of the authors is a consultant for the company.

Another study of more than 282,000 people in Wales found that those who received a different shingles vaccine had a 22.4% lower risk of being diagnosed with dementia in the seven years following vaccination compared with those who didn’t receive the vaccine. That research, which was led by researchers at Stanford University, was published last year in the journal Alzheimer’s & Dementia.

“We are seeing different groups, different methodologies, coming up with not exactly the same results, but broadly similar results,” said Phil Dormitzer, global head of vaccines research and development and infectious-disease research at GSK. The Shingrix vaccine is the only shingles vaccine available for use in the United States.

One out of three people will get shingles in their lifetime, according to the Centers for Disease Control and Prevention. The infection is a reactivation of the chickenpox virus, which can lie dormant in the nervous system. While rarely life-threatening, shingles causes distressing symptoms including a painful rash with blisters that can last for several weeks. It can also lead to blindness and to neurological pain that can persist for months or years.

Vaccine experts say the possibility of a connection between the shingles vaccine and reduced risk of dementia makes sense.

“I think it’s real,” said Paul Offit, a physician and professor of vaccinology at the University of Pennsylvania. He’s also a member of the Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee.

Offit and other experts said there are two possible reasons that the shingles vaccine might protect against dementia. First, previous research suggests that herpes infection might play a role in the development of dementia.

Shingrix dramatically decreases the reactivation of the herpes virus that causes chickenpox. It’s 97% effective at preventing shingles in people ages 50 to 69 with healthy immune systems, according to the CDC.

Experts also hypothesize there might be something about the particular way Shingrix stimulates the body’s immune system against shingles that decreases the chances of dementia.

Hotez, the vaccine expert in Texas, said that if more studies show that Shingrix protects against dementia, it could be “another carrot to induce people to want to get it.”

Only 18.6% of people in the United States who are aged 50 and older have received at least one dose of Shingrix, which is given in two doses, according to CDC data from 2021. The CDC also recommends the vaccine to anyone age 19 and older with a weakened immune system.

Dormitzer, the GSK scientist, said the company is doing more studies to see if there truly is a relationship between the shingles vaccine and preventing dementia.

“We have a very interesting clue here,” he said. “We have more work to do at this point.”

William Schaffner, a physician and infectious-disease researcher at Vanderbilt University School of Medicine, said that if the relationship withstands further scrutiny, it would be “big news – capital B, capital N, because at the moment, we have a very limited number of things we can do to prevent or intervene on behalf of people who have Alzheimer’s.”

Elizabeth Cohen, MPH, is a medical journalist and the author of “The Empowered Patient: How to Get the Right Diagnosis, Buy the Cheapest Drugs, Beat Your Insurance Company, and Get the Best Medical Care Every Time.”