Millions worldwide suffer from herpes, with painful outbreaks caused by the highly contagious HSV virus. While there’s no cure, a glimmer of hope shines through as new vaccine candidates are being developed to prevent these infections altogether.
Current treatments focus on managing outbreaks with medication, but a successful vaccine could change the game. It’s estimated that a vaccine against genital herpes alone could prevent 350,000 new cases each year, a significant public health impact.
Researchers are actively working on several promising vaccine candidates, aiming to overcome challenges that plagued previous attempts.
What is herpes?
Herpes simplex virus (HSV) is a common culprit behind those pesky blisters on your lips (cold sores) or genitals. It’s not just a single virus, but a duo: HSV-1 and HSV-2.
HSV-1 loves the mouth, causing those familiar tingly cold sores. But it can also venture south and cause genital sores.
HSV-2 prefers the genital area, but it can also cause oral sores through oral sex.
Once infection occurs the virus becomes a lifelong resident, occasionally flaring up with painful sores or blisters. In rare cases, it can cause serious infections like meningitis and encephalitis.
But HSV is just one branch on the big family tree of herpesviruses.
Cure
There’s no cure for herpes. However, researchers are hoping that gene therapy could potentially open the door for a future herpes cure.
For now, 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.
Vaccines in pipeline
Vaccines are currently being researched to target both HSV-1 and HSV-2. Most are being developed for HSV-2 since it can cause more dangerous infections. 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.
Delta gD-2
X-Vax Technology has developed an HSV vaccine that works differently than other vaccines studied in the past. Other vaccines have targeted a protein on the virus needed to enter and infect your cells. But this vaccine removes that protein, triggering a different type of immune response that may be more effective. It’s currently known as “delta gD-2.”
In 2021, X-Vax Technology announced it would be submitting an investigational new drug (IND) application to the FDA. If approved, the vaccine could begin clinical trials in people. It would be studied for the prevention of HSV-1 and HSV-2. And it may have potential as a treatment vaccine, too.
mRNA-1608
Messenger RNA (mRNA) technology has shown potential for vaccines against several types of infections — including HSV. Although it’s still in preclinical development, Moderna is working on an mRNA HSV-2 vaccine known as “mRNA-1608.”
So far, animal studies suggest the vaccine may trigger a strong immune response against the virus. But this has yet to be confirmed in people.
BNT163
BioNTech’s HSV-2 vaccine (BNT163) seems to be further along in the process. It also uses mRNA technology to prevent infection. The company expects to launch phase 1 clinical trials before the end of 2022.
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.
Recently, the company launched a vaccine candidate study. Researchers will determine baseline characteristics of participants to help them design human trials for the vaccine.
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 to make sure that it’s safe and effective in humans. This process typically takes several years, so it will likely be some time before we see an HSV vaccine come to market.
