Is a Herpes Vaccine Currently In the Works?

Herpes simplex viruses (HSV) are part of a larger family of herpesviruses. They’re very common — affecting about 90% of adults worldwide. And they can cause painful sores in or around the mouth or genitals. Unfortunately, there’s no cure for HSV infections, and people need to manage their outbreaks with medications. Several HSV vaccines have been tested. But none have been brought to market at this point.

Yet companies are still trying to figure out how to prevent these infections through vaccination — and with good reason. Modeling suggests that an HSV vaccine for the virus that commonly causes genital herpes could prevent as many as 350,000 new infections every year.

There are several HSV vaccine candidates in the pipeline. The hope is that they’ll show promise where previous prospects have fallen short. Here, we’ll discuss new and ongoing research in this area and if we can expect a vaccine to be available in the near future.

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What is the herpes simplex virus (HSV)?

HSV is a virus that can cause painful ulcers in your mouth (cold sores) or on your genitals. There are two main herpes simplex viruses — HSV-1 and HSV-2. HSV-1 infections most commonly affect your mouth, but they may also result in sores on your genitals. HSV-2, on the other hand, primarily affects your genitals.

Once you’ve been infected with HSV, the virus stays in your body long term. This can cause sores or blisters to appear periodically (called an outbreak). In rare cases, it can cause life-threatening infections like meningitis and encephalitis.

When you think of herpesviruses, HSV is likely what comes to mind. But both types of HSV are actually part of a larger family of herpesviruses, including:

• Varicella-zoster virus (causes chickenpox and shingles)

• Epstein-Barr virus (causes mononucleosis)

• Cytomegalovirus

Is there a cure for herpes?

Unfortunately, there’s no cure for herpes at this time. However, researchers are hoping that gene therapy could potentially open the door for a future herpes cure. So far, results from animal studies have been promising.

Until then, HSV infections are managed with prescription antiviral medications, like Valtrex (valacyclovir) or Zovirax (acyclovir). These medications can help resolve blisters when they appear. And some people take them daily to prevent outbreaks, too.

However, some people may find that available medications don’t work well for them. And condoms may not cover all areas where genital blisters appear to avoid transmitting the infection to your partner. This has prompted research into whether a vaccine for these viruses is possible.

Why is creating an HSV vaccine so difficult?

Herpesviruses can live in your body undetected. This means your immune system doesn’t react to them right away. The longer the virus goes undetected, the more difficult it is to make an effective vaccine. Even though we have vaccines for other illnesses caused by herpesviruses, such as chickenpox and shingles, HSV does a better job of evading the immune system.

When scientists make vaccines, they target the part of your immune system that recognizes an invader — like a virus or bacteria — in your body. The vaccine then teaches your body how to kill the invader before it makes you sick. If the immune system doesn’t react to HSV right away, a vaccine cannot teach your body how to protect you.

HSV vaccine studies in animals have had good results. But when these vaccines were studied in humans, they didn’t work as well. That’s when pharmaceutical companies had to restart their research attempts.

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Has an HSV vaccine ever been tested on humans?

Yes. Human studies of several vaccines have occurred in the last few years. People who participated in the vaccine trials didn’t have many side effects. But they didn’t see much benefit either. Even though earlier studies didn’t work out, several vaccines are still being tested.

Are there any herpes (HSV) vaccines currently being studied?

Yes, vaccines are currently being researched to target both HSV-1 and HSV-2. Most are being developed for HSV-2. But since the viruses are so similar, an HSV-2 vaccine would also likely work to prevent or treat HSV-1, too.

There are two types of HSV vaccines being studied:

• Treatment vaccines: These vaccines would benefit people who’ve already been infected with HSV. They could improve symptoms, help blisters heal faster, and lower the risk of spreading the virus to other people.

• Preventative vaccines: These vaccines would benefit people who haven’t been exposed to HSV. They would train your immune system to prevent an HSV infection if you were exposed to the virus in the future.

Just as with any vaccine, all HSV vaccines will need to go through three types of clinical trials — phase 1, 2, and 3 trials — before being approved by the FDA. This to make sure that they’re safe and effective for humans. This process typically takes several years. So, it will likely be some time before we see an HSV vaccine come to market. Here are a few HSV vaccine candidates being studied right now.

mRNA-1608

Messenger RNA (mRNA) technology has shown potential for vaccines against several types of infections — including HSV. Moderna is working on an mRNA HSV-2 treatment vaccine known as “mRNA-1608.” 

Currently, the mRNA-1608 vaccine is being studied in a phase 1/2 clinical trial in adults ages 18 to 55 with a history of recurrent HSV-2 genital herpes. Researchers are testing several different doses to assess safety and immune response. The study is expected to be completed in June 2025.

BNT163

BioNTech’s HSV-2 vaccine (BNT163) is also making progress. It uses mRNA technology to prevent infection. The company launched a phase 1 clinical trial in December 2022 studying the vaccine in adults ages 18 to 55 without a history of symptomatic genital herpes. The study is expected to be completed in December 2025.

RVx-201

RVx-201 is a treatment vaccine developed by Rational Vaccines. In animal studies, it was shown to significantly reduce the number of symptomatic days by 45% compared to 24% with a different HSV vaccine. It also reduced recurrent genital herpes lesions.

In 2022, the company launched a vaccine candidate study. The study was intended to help researchers determine baseline characteristics of participants and their willingness to participate in a clinical trial. The study has since been completed, but no further updates are available. The company is also researching preventative vaccines for HSV-2 (RVx-2001) and HSV-1 (RVx-1001).

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Written by:

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP

Nicole E. Cieri-Hutcherson, PharmD, BCPS, NCMP, has over a decade of experience as a pharmacist, professor, and researcher. She was a full-time clinical professor in the pharmacy practice department at D’Youville School of Pharmacy before subsequently joining the faculty of the pharmacy practice department at the University at Buffalo School of Pharmacy and Pharmaceutical Sciences.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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