What You Need to Know About the COVID Vaccine and Herpes

Whether you're thinking of getting vaccinated, have already gotten your shot, or are prepping for your next booster, you might be reading online about what you can expect when it comes to the side effects of the COVID-19 vaccine.

Plenty of rumors have been popping up, but perhaps the most poignant and alarming one is that the COVID vaccine may cause herpes. This was thanks in large part to a study published in 2021 that found a connection between the COVID vaccine and activation of the herpes zoster virus. You may have also seen anecdotal reports from vaccine recipients saying they had a herpes simplex outbreak after getting the jab.

What this means, and the most important thing to know: The COVID-19 vaccine cannot give you herpes, but it can reactive a herpes virus if you're already infected.

If you're already confused, it's okay. Herpes is a complex virus that gets even more complicated when you add other variables to the mix, but here is some information that can help.

The Concern About the COVID Vaccine and Herpes

First, let's talk about how the COVID vaccine became linked to herpes in the first place.

A 2021 study published in Rheumatology looked at the effect of mRNA-based vaccines (such as the coronavirus vaccine) on patients with autoimmune inflammatory rheumatic diseases (AIIRD) — a group of diseases that cause your immune system to attack your joints, muscles, bones, and organs, and include rheumatoid arthritis, systemic lupus erythematosus, Sjögren syndrome, and polymyositis.

The study reported that out of 491 patients with an AIIRD, six adult women developed herpes zoster infections, aka shingles, within three to 14 days after receiving the Pfizer vaccine — five developed symptoms after their first dose and one after receiving the second dose. The researchers noted that these six women accounted for only 1.2 percent of the 491 patients with AIIRD involved in the study. Meanwhile, zero patients in the control group (read: people who do not have an AIIRD) experienced a herpes zoster infection after vaccination.

Shortly after the study was released, the information was published in the New York Post, where it began making the rounds online. And even though the study's lead author, Victoria Furer, M.D., did tell the Jerusalem Post that there's no causal link between the two (herpes and the vaccine), she mentioned that the vaccine could be a "trigger" to patients with similar pre-existing conditions. This was enough to create a little internet frenzy, particularly among those who are already skeptical of getting the vaccine in the first place.

Herpes Zoster vs. Herpes Simplex

Herpes zoster (or HZ) is another name for shingles. It's a viral infection that usually appears as a painful red skin rash and can cause nerve damage and longer-term burning and pain if left untreated. It occurs as a result of the varicella-zoster virus, the virus that causes chicken pox, according to the Mayo Clinic. The first time you're infected with the virus, it presents as chicken pox; on subsequent reactivations, it's considered herpes zoster or shingles (and comes with different symptoms), even though it's the same virus.

The HZ/shingles rash can develop anytime after you've been previously exposed to the virus. If you were born before the advent of the chicken pox vaccine in 1995, you may have had it as a child, and the virus is now lying dormant in your system — meaning, it can "reactivate" at any time and result in HZ/shingles symptoms. If you're vaccinated against chicken pox — and more than 90 percent of U.S. children are currently, according to National Immunization Survey data — you can still get shingles later on in life, since the chicken pox vaccine contains small, weakened amounts of the varicella virus.

That said, it's not super common, as Anne A. Gershon, a professor of pediatric infectious disease at Columbia University, explained to Scientific American. "The virus has been altered so the vaccine rarely causes symptoms, but once you've been immunized and after the natural infection, you carry the virus in your neurons for the rest of your life," she said.

Herpes simplex (HSV-1 or HSV-2), the viruses that can cause cold sores or genital herpes, respectively, are not the same virus as herpes zoster, though they all come from the same large family of viruses. Both HSV-1 and HSV-2 are spread through skin-to-skin contact, and they are slightly different strains from the same viral family. HSV-1 typically thrives in the oral mucus membranes — which is why it typically pops up as cold sores, which are sometimes called fever blisters — while HSV-2 typically prefers the genital mucus membranes. (That said, it is possible to have HSV-1 genitally and HSV-2 orally.)

Herpes is common — like, incredibly common — even though STIs, in general, are often neglected in sexual education or are unnecessarily (and unfairly!) shrouded in cultural shame and stigma. About one in every six U.S. adults has HSV-2, and an estimated 50 to 80 percent of the adult population is currently living with HSV-1 (and 90 percent will be exposed to the virus by the time they hit 50). However, many people living with herpes don't know they have it. Research shows that somewhere between 75 and 90 percent of people with HSV-2 report being completely asymptomatic.

Symptoms of herpes can also mimic those of other STIs or ingrown hairs, pimples, or even the flu, so even if you do show symptoms, you might not be aware that it's a herpes outbreak, according to the American Family Physician. Add to the mix that the virus can lay dormant for years without symptoms or outbreaks, and it's easy to understand how and why someone might not even realize they have it.

FYI, both herpes zoster and simplex viruses are contagious. Shingles are only contagious to people who aren't already immune (meaning, you've never had chicken pox or weren't vaccinated for it), according to the Mayo Clinic. Transmission usually occurs if the person makes direct contact with the open sores of the shingles rash. If the person becomes infected, they'll develop chicken pox, not shingles — because it's their first infection. Herpes simplex, on the other hand, can be spread through direct contact with the virus, such as through saliva or genital secretions from kissing or having vaginal, anal, or oral sex with someone who has the virus.

Is Herpes Actually a Risk of the COVID-19 Vaccine?

Okay, so what does this all have to do with the COVID vaccine? The long and short of it is nothing, really, unless you've already been infected with any of the herpes viruses — and even more so if you're immunocompromised as well.

Both types of herpes viruses discussed here (zoster and simplex) are known to be triggered (aka reactivated) during times of stress. As with all vaccines, the COVID vaccine causes an immune response — which is essentially a stress response — since your body is coping with and building a defense against invaders. The vaccination could be enough to prompt a reaction or outbreak in people who already have the herpes virus — and it seems to be more of a risk for people who also have a lowered immunity due to an AIIRD or other autoimmune conditions in addition to an existing herpes infection. Again, there's no way for the vaccine to cause herpes; it only has the potential to reactivate it if you already have the virus in your body.

And that's not because the COVID-19 vaccine is doing anything notably crazy to your body. Other common physical and mental stressors — from having a common cold to going through a rough patch at work or a break-up — are thought to be enough to trigger this sort of reactivation in both herpes zoster and simplex, according to research.

"Anything stressful to the body can potentially result in the reactivation of any type of herpes," says Felice Gersh, M.D., ob-gyn, founder/director of the Integrative Medical Group of Irvine in Irvine, California, and author of PCOS SOS Fertility Fast Track. "The COVID vaccines have a significant degree of variance in their effects on different people. For some, the inflammation it creates in the body could potentially lead to a herpes outbreak," she shares. "It certainly is plausible."

It's also worth mentioning that getting COVID might also lead to the reactivation of the previously dormant varicella-zoster virus. Long COVID symptoms — which may affect anywhere from 5 to 50 percent of people who contract the virus, according to an article in Nature — are highly variable, and may last for months or years after the original illness. One study found signs that varicella-zoster virus and Epstein-Barr virus (which causes mononucleosis) may have been reactivated in participants with Long COVID who had previously contracted one of these two herpesviruses.

As with many COVID-related things, more research is needed, says Dr. Gersh. However, if you've been diagnosed with either type of herpes virus and you're worried about an outbreak, you can talk to your doctor about taking herpes antiviral medications (which may help prevent outbreaks and reduce their severity) prophylactically — i.e. as a preventative measure.

Though outbreaks directly related to the vaccine still appear to be pretty unlikely, according to Dr. Gersh, if you do get one, here's how to cope. "In general, recurrent herpes outbreaks last about a week," she says. "Antiviral medications taken early can reduce the severity and duration. Taking ibuprofen can help, as can warm compresses or baths. Topical vitamin E oil or CBD salve might help ease symptoms too. Best advice: Take one of the herpes antiviral meds ASAP when symptoms begin," details Dr. Gersh.

As mentioned above, it's entirely possible to have the herpes virus and not even realize — if you've ever had a cold sore in your life, it means you have HSV-1. If you didn't know you had it and suddenly have an outbreak post-COVID vaccine, there's no reason to feel embarrassed or ashamed. Keeping an eye out for any symptoms is crucial, as well as checking in with your doctor for anything that comes on suddenly or severely. The TL;DR is that herpes is super common and, unfortunately, shrouded in societal stigma and secrecy, but there's no reason to overly worry if you do notice an outbreak — vaccine or not.

And to say it again: The COVID-19 vaccine cannot cause herpes — and, FWIW, Dr. Furer still advises people to get vaccinated, even if they do have herpes or other autoimmune conditions. Even if it triggers an outbreak (which sucks) it's still protecting you from COVID-19, which has the potential to be a lot worse, even deadly. Further research on these isolated reactions is necessary, she noted in the interview with the Jerusalem Post, and patients who are concerned should talk to their doctor before getting their COVID-19 shot.

"We should not scare people," Dr. Furer told the outlet. "The overall message is to get vaccinated. It is just important to be aware," she added.

As for assuaging fears about the vaccine's overall safety, it's also important to remember that millions of people have safely received the vaccine, according to the Centers for Disease Control and Prevention (CDC), and adverse effects have been few and far between thus far. Checking in with your doctor if you are concerned is never a bad idea.

The information in this story is accurate as of press time. As updates about coronavirus COVID-19 continue to evolve, it's possible that some information and recommendations in this story have changed since its initial publication. We encourage you to check in regularly with resources such as the CDC, the WHO, and your local public health department for the most up-to-date data and recommendations.