We asked experts to break down the results of a small new study, which found that herpes zoster might be a side effect of getting vaccinated.

By Korin Miller
April 21, 2021
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A new study is getting plenty of attention after researchers linked a particular form of herpes to the COVID-19 vaccine in a handful of people.

The study, published in the journal Rheumatology, analyzed side effect data from 491 people with autoimmune inflammatory rheumatic diseases (AIIRD) who received the Pfizer-BioNTech vaccine.

The researchers found that six of the patients with AIIRD (or 1.2%) developed herpes zoster—aka shingles—within several days of receiving the vaccine. Four of the patients had rheumatoid arthritis, one had Sjogren's syndrome, and another had a connective disease. All of the patients were women, and five of the reactions happened after the first vaccine dose.

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Credit: Getty Images

The herpes zoster infection was mild in the majority of cases, although one patient had a case of herpes zoster ophthalmicus, which is when the virus impacts the eye. Five of the patients were treated with antiviral medication and had no symptoms up to six weeks later. Five of the patients completed their second dose of the vaccine without any other issues.

It's easy to get freaked out when you hear the word "herpes" in the same sentence as "COVID-19 vaccine," but experts say that this is not as shocking—or surprising—as it seems at first. Here's what you need to know.

First, a primer on herpes zoster

Herpes zoster is another word for shingles, i.e. an outbreak of a rash or blisters on the skin. It's triggered by the same virus that causes chickenpox, the varicella-zoster virus, the National Institute of Neurological Disorders and Stroke (NINDS) says. For the record: This is not the same thing as genital herpes or oral herpes; those two conditions are caused by different herpes viruses.

What are the symptoms of herpes zoster?

At first, people with shingles may have a burning, itching, numb, or tingling pain that can be severe, NINDS says. It usually happens on one side of the body. People develop shingles after they've had a previous chickenpox exposure. When the virus reactivates, it causes shingles.

After a few days, a rash of fluid-filled blisters will appear in one area on one side of the body, NINDS explains. Shingles most commonly shows up in a band called a dermatome that goes from one side of your midsection around your waistline.

The pain from shingles can vary—some people mostly itch; Others can have pain from a gentle touch.

How can the COVID-19 vaccine cause herpes zoster?

It's important to point out that the study didn't prove the COVID-19 vaccine causes shingles. Instead, the study found a link, and even the study authors wrote that the association needs to be researched more.

That said, this connection isn't shocking to doctors. "People with autoimmune disorders that are on immunosuppressant medications are at higher risk of having shingles," infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland, tells Health. Vaccines can also impact the immune system, and "there have been reports of vaccines causing shingles in the past," Dr. Adalja says.

"This can happen with the flu vaccine and others," Richard Watkins, MD, an infectious disease specialist and a professor of internal medicine at the Northeast Ohio Medical University, tells Health. And if someone already has an autoimmune condition, they may be at greater risk of shingles, Dr. Adalja adds.

Dr. Adalja calls the study "well done" and says it simply shows that "this phenomenon can occur after the COVID-19 vaccine as it has with others."

How concerned should you be about getting herpes zoster from the COVID-19 vaccine?

While it's possible to get herpes zoster after being vaccinated against COVID-19, Dr. Adalja explains that overall risk is low—especially if you don't have an autoimmune condition.

Herpes zoster can be treated with antiviral medications (usually valaciclovir) and most people recover just fine, he says.

If you're particularly concerned about your risk of developing shingles after getting the COVID-19 vaccine, Dr. Adalja says you can talk to your doctor about receiving the herpes zoster vaccine first. Just know this: Because the herpes zoster vaccine is recommended for people who are 50 and older, it's unlikely your insurance will cover it if you're below that age.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDCWHO, and their local public health department as resources.

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