Shingles—Herpes Zoster—Infection May Be Linked to the COVID-19 Vaccine

It's easy to grow concerned when you hear the word "herpes" in the same sentence as "COVID-19 vaccine." But really, this is not as shocking—or surprising—as it seems at first. Several studies have suggested a link between COVID-19 vaccines and the herpes zoster virus—the virus that causes shingles. Here's what to know about the risk of developing herpes zoster (HZ) infection following mRNA COVID-19 vaccination.

A Primer on Herpes Zoster

HZ is another word for shingles, which is 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: HZ is not the same thing as genital herpes or oral herpes. Genital and oral herpes are caused by different herpes viruses, namely herpes simplex virus 1 or 2.

Cases of Herpes Zoster Following COVID-19 Vaccination

One of the earliest reports of HZ infection post-COVID-19 vaccination was published in April 2021 in the journal Rheumatology. The study 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 HZ 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.

The HZ 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.

The Risks Compared to Other Vaccines

In February 2022, a study published in the British Journal of Clinical Pharmacology looked at the relative risk of HZ reporting in mRNA COVID-19 vaccine recipients compared to influenza vaccine recipients. Researchers used the VigiBase database from the World Health Organization (WHO). This global database contains about 27 million spontaneous reports of suspected adverse drug reactions collected by national drug authorities in more than 130 countries.

The authors concluded that, when compared to influenza vaccines, mRNA COVID-19 vaccines were associated with a significantly higher reporting of HZ, especially in patients over 40 years old. However, the researchers wrote, the HZ reactions following mRNA COVID-19 vaccination were usually mild and infrequent as reflected by the billions of doses of COVID-19 vaccine administered so far.

Several subsequent studies also reported a link between the COVID-19 vaccines and HZ. A March 2022 study published in the American Journal of Ophthalmology Case Reports reported three cases of patients not on immunosuppressive therapy who presented with HZ after COVID-19 vaccination. The conclusion was that HZ may be a side effect of mRNA COVID-19 vaccination, but more research is required.

Reactivation of Shingles

In May 2022, a study published in the journal Cureus reported on 10 incidences of HZ reactivation in people within seven to 21 days of getting the COVID-19 vaccine. The study found that increased age was the most important risk factor for HZ reactivation, but other risk factors included immunocompromised states, such as HIV infection, trauma, stress, or concomitant diseases including malignancy (cancer), liver disease, or chronic kidney disease.

The Cureus authors wrote that the fundamental reason for HZ reactivation was unknown. However, with the HZ reactivation occurring within one to 21 days after vaccination, COVID-19 vaccination was a likely cause for the reactivation of latent HZ. None of the patients had any other risk factor for developing HZ.

As the Cureus authors highlight, the incidence of HZ infection after COVID-19 vaccination is not a common occurrence. At the time of their study, the authors noted that the United States Vaccine Adverse Event Report System (VAERS) had reported 2,512 cases of HZ (1.3%) of total reported events after the Pfizer-BioNTech vaccine, 1,763 cases (0.9%) after the Moderna vaccine, and 302 (0.7%) after the Johnson & Johnson vaccine.

Shingles Symptoms

At first, people with shingles may have a burning, itching, numbness, 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 previous exposure to the varicella-zoster virus. 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 show 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.

COVID-19 Vaccine and Herpes Zoster Link

It's important to point out that none of the studies prove the COVID-19 vaccine caused shingles. Instead, they found a link, and most of the study authors wrote that the association needs to be researched more. The Cureus authors wrote, "These cases highlight the significance of continuing to examine vaccine safety during the COVID-19 pandemic's ongoing mass vaccination campaign."

That said, this connection isn't shocking to healthcare providers. "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, told Health. Vaccines can also impact the immune system, and "there have been reports of vaccines causing shingles in the past," Dr. Adalja said.

"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, told Health. And if someone already has an autoimmune condition, they may be at greater risk of shingles, Dr. Adalja said.

Dr. Adalja said, "this phenomenon can occur after the COVID-19 vaccine as it has with others."

How Concerned Should You Be?

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

HZ can be treated with antiviral medications (usually valacyclovir) and most people recover just fine, Dr. Adalja said.

If you're particularly concerned about your risk of developing shingles after getting the COVID-19 vaccine, Dr. Adalja said, you can talk to your healthcare provider about receiving the HZ vaccine first. Just know this: Because the HZ vaccine is recommended by the Centers for Disease Control and Prevention (CDC) for people aged 50 years 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 CDC, WHO, and their local public health department as resources.