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(CNN) — Although the two-dose shingles vaccine may force you to lay low for a day or two after getting the shot, it’s over 90% effective against this painful disease and its complications.
Now it turns out the shingles vaccine may have an added benefit: reducing the risk of dementia, according to a new study published in the journal Nature.
It’s a welcome discovery for people who have already received the shingles vaccine. And knowing the vaccine has additional benefits may convince more people 50 and older (and those 19 and older with weakened immune systems) to get it.
To help make sense of the study’s takeaways, I spoke with CNN wellness expert Dr. Leana Wen. I wondered how convincing the results are and how the shingles vaccine might be beneficial to brain health. In addition, who should get the shingles vaccine? If someone already had shingles, should they still get it?
Wen is an emergency physician and adjunct associate professor at George Washington University. She previously served as Baltimore’s health commissioner.
CNN: To start, what is shingles?
Dr. Leana Wen: Shingles, or herpes zoster, is a viral infection caused by the varicella-zoster virus. This is the same virus that causes chickenpox, and people who have had chickenpox still carry the virus in their bodies. This virus can be reactivated many years later and manifests as shingles.
The major symptom is a painful rash that commonly appears as a band of blisters localized to one area on the body . Where that is depends on the person; shingles can occur virtually anywhere, including over the face. Most people who develop shingles have it once in their lifetimes, although some people can have it more than once. Some serious complications are associated with shingles, including long-term nerve pain known as postherpetic neuralgia.
CNN: Is shingles contagious?
Wen: You cannot get shingles by being in contact with someone who has shingles. However, someone who never had chickenpox or didn’t get the chickenpox vaccine can get the varicella-zoster virus through direct contact with a person who has shingles. An individual who has active blistering should keep the rash covered to prevent spread.
CNN: What vaccine is recommended to prevent shingles? Who should get it?
Wen: The US Centers for Disease Control and Prevention recommends two doses of the recombinant zoster vaccine, called Shingrix, for adults 50 and older . This age recommendation is because the chance of the virus reactivating increases with age. The CDC also recommends Shingrix for people 19 years and older who have weakened immune systems. The two doses should be spaced out between two and six months.
CNN: What are potential side effects?
Wen: Similar to other vaccines, the Shingrix vaccine can lead to pain, redness and swelling at the injection site in the first day or so after vaccination. Some people may experience fatigue, headache, fever, shivering and upset stomach. These side effects generally subside within two to three days following the shot and are far preferred to getting shingles.
CNN: How convincing are the new study’s findings that the shingles vaccine has this additional benefit of reducing dementia risk?
Wen: This study follows several other studies that identified a possible link between the vaccine and lowering dementia risk. The design of this one is particularly intriguing because it took advantage of a “natural experiment” that occurred in Wales as it rolled out its shingles vaccination program in 2013. At that time, in part due to limited vaccine supply, government officials decided that only Welsh adults born on or after a very specific date — September 2, 1933 — were eligible for the shingles shots. People born before that date were ineligible.
This rule set up a fascinating opportunity to directly compare the health outcomes of two groups of individuals over time. It eliminates a bias found in many other studies of vaccine outcomes, which is that those adults who choose to receive vaccines may otherwise engage in more health-promoting behaviors than those who do not.
In this study, researchers followed about 280,000 participants who were ages 71 to 88 and were without dementia at the onset and tracked their diagnosis of dementia for seven years. Nearly half of the participants eligible for the vaccine received it. The researchers found that people who received the shingles vaccine had a 20% reduction in relative dementia risk compared with those who did not.
To make sure there weren’t other confounding factors, researchers accounted for things such as how often the participants sought medical care. They also did a sub-analysis looking at those born in the same year, but with the arbitrary date of the September 2 birth cutoff, and found similar results, meaning that in this sub-analysis, they were comparing people who are virtually the same age .
I think these are quite important findings. There are many pharmaceutical interventions being studied to delay or slow the development of dementia. If any of them found an effect size of 20%, they would be deemed substantial. Here is a relatively low-cost intervention that is already recommended to prevent another disease — shingles — that could have this added benefit.
CNN: How could the shingles vaccine benefit brain health?
Wen: Dementia is a broad category that includes many different causes. Alzheimer’s disease is the most common type of dementia, accounting for 60% to 80% of cases, according to the CDC. A lot is still unknown about the cause of Alzheimer’s, but one hypothesis is that it is driven by brain tissue inflammation. Shingrix can reduce neuroinflammation caused by virus reactivation and perhaps can help reduce brain inflammation, too.
CNN: Is someone already had shingles, should they get the vaccine? What if they have had chickenpox?
Wen: You should get Shingrix even if you’ve had shingles, according to the CDC. In addition, if you had the previous version of the vaccine, called Zostavax, you should still get Shingrix because it’s more effective. Zostavax was licensed and recommended in the US in 2006. It is no longer available here due to the availability of Shingrix, which was approved in 2017. If you are not sure whether you got Zostavax or Shingrix, you should try to find your immunization records. Chances are that if you got a vaccine against shingles between 2006 and 2017, it was Zostavax. It was removed from the US market as of November 18, 2020.
This recommendation is regardless of whether someone is known to have had chickenpox in the past. That’s because more than 99% of Americans born on or before 1980 are estimated to have chickenpox, even if they don’t know that they have had it.
Unfortunately, not many people are getting the benefits of the Shingrix vaccine right now. In 2021, the CDC estimates that only 15.4% of adults 50 and above had had two doses of Shingrix. Perhaps this study could help to convince those eligible to get the shot. Not only can it prevent shingles and long-term nerve damage that could accompany shingles, it also may have a protective effect on their brain to reduce the risk of developing dementia.
