Progress in Developing a Herpes Vaccine

The search for a vaccine to protect against oral and genital herpes has been a long one. Researchers have been experimenting with possible vaccines since at least the early 1930s. To date, they've seen little success. While herpes vaccines have been successful in mice, they've been largely unsuccessful in human trials.

This article explains the steps that have been taken thus far to develop vaccines for oral and genital herpes, the reasons why these vaccines are important, and the roadblocks keeping researchers from better preventing or controlling herpes infections.

Herpes virus
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Where Herpes Vaccine Research Stands

Although some vaccines for these herpes types have initially appeared to have promise, stringent testing has shown them to be no better than a sham vaccine, or placebo.

With that said, newer approaches to vaccine development—including genetic editing—have begun to show promise in early-stage animal research, offering a glimpse of hope of a possible breakthrough.

Existing Herpes Vaccines

Technically speaking, there are already herpes vaccines on the market. They just don't protect you from herpes simplex virus (HSV) type 1 (the type most commonly associated with oral herpes) or HSV type 2 (the type most commonly associated with genital herpes).

Rather, the two vaccines currently available protect against a type of herpes virus known as varicella-zoster virus (VZV), more commonly called the chickenpox virus.

Once a chickenpox infection resolves, the virus remains in a dormant (latent) state. It does so in a cluster of nerve cells called the dorsal root ganglion, where it could reactivate later in life. If it does, it causes shingles (herpes zoster).

The shingles vaccine and chickenpox vaccine both guard against the virus, but in different ways:

  • The chickenpox vaccine is typically given in early childhood to protect you from becoming infected with VZV.
  • The shingles vaccine is given from the age of 50 to prevents the reactivation of VZV.

These are similar to the two types of vaccines that have been proposed to protect against oral and genital herpes. One type aims to prevent the virus from infecting people who've never had it, while the other aims to protect against outbreaks in people who already have herpes.

Protecting people who have had herpes from future outbreaks is important because once you're infected with a herpes virus, it stays in your body forever. It goes dormant, but can suddenly reactivate at any point, bringing on symptoms again.

An adult in their 60s, for example, might develop shingles due to a reactivation of VZV that they acquired when they had chickenpox as a child.

Oral and genital herpes outbreaks can recur in the same way.

Recap

The chickenpox vaccine protects you from a type of herpes. The shingles vaccine protects you from reactivation of that same virus. However, this is not the type of herpes associated with oral or genital cases.

Herpes Vaccine Priorities

Theoretically, it makes sense that a vaccine could work to prevent oral and genital herpes outbreaks. After all, in many people, the immune system controls herpes infections so that they never have symptoms.

This makes herpes a good target for a therapeutic vaccine—that is, one that treats rather than prevents disease. However, the herpes simplex viruses have proven to be difficult to control with vaccines.

In 2017, the World Health Organization (WHO) defined a series of priorities for developing a herpes vaccine:

  • Reduce the number of people who become infected with human immunodeficiency virus (HIV) due to a herpes genital infection. (Having genital sores increases your risk of getting HIV.)
  • Reduce the number of people negatively affected by HSV by reducing physical symptoms, psychological symptoms, and serious consequences such as infection in newborns (neonatal herpes).
  • Reduce the impact of herpes infection on reproductive health.

The WHO suggests that two types of vaccines could be useful for herpes simplex infections:

  1. Prophylactic vaccines, like the chickenpox vaccine, would help prevent people from ever getting herpes.
  2. Therapeutic vaccines, like the shingles vaccine, would reduce the number of outbreaks.

Recap

Developing vaccines that can prevent oral or genital herpes infection and reactivation are worldwide goals. This is not just because of a desire to reduce complications of HSV itself, but to address the increased risk of HIV infection that comes with genital herpes.

Barriers and Successes

Some promising trials of herpes vaccines have been performed. However, to date, no human trials have shown high enough efficacy to bring a herpes vaccine to market.

Challenges

Scientists have several hurdles to face when developing a vaccine to protect against oral or genital herpes.

No animal model perfectly replicates HSV infection in humans. Several vaccine candidates have shown promise in animal studies but have, thus far, not been effective in clinical trials in humans.

Aside from mice, rabbits and guinea pigs are also being used to develop therapeutic herpes vaccines (for eye and genital herpes, respectively). Early results have been promising, but current animal models still don't do a great job of showing how the disease progresses in humans.

Herpes vaccines are also difficult to study for several other practical reasons:

  • Limited study population: Researchers need to test a lot of people to see if a vaccine works. Those people can be hard to find.
  • Asymptomatic infection: Because many infected people never have herpes symptoms, assessing the effectiveness of a preventive vaccine means having to actively test to see whether they've been infected with the virus since getting the shot.
  • Viral shedding: Scientists have to test the possibility that the virus will be shed, or release particles that can infected others. Low viral shedding translates to a lower risk of infections.

Addressing any of these factors can make vaccine trials slow-going, burdensome, impractical, and expensive.

Advances

A 2020 study from researchers from the University of Cincinnati, Northwestern University, and the University of Nebraska-Lincoln offers hope of a possible breakthrough.

According to the research, a genetically modified form of herpes simplex virus type 1 was able to prevent symptoms of herpes simplex virus type 2 in guinea pigs. The response was far more robust than seen with any herpes vaccine study to date. It significantly slowed the virus's replication and showed less viral shedding.

Another research team at the University of California, Irvine, School of Medicine proposed the use of lasers as part of the vaccination procedure. Their goal was to stimulate the development of immune cells in the layers of the skin where herpes reactivation occurs.

The procedure involved mice. It, too, showed promise in preventing genital herpes, improving the effect of an experimental vaccine.

Although it's far too soon to tell whether the studies will lead to a successful vaccine, these advances are considered significant.

Recap

The lack of a vaccine for oral or genital herpes is not for a lack of effort. Several issues, including the poor translation of results in animals to results in humans, have made development challenging.

Summary

Putting an end to oral and genital herpes would have a far-reaching impact on the health of people around the world. The virus increases the risk of HIV, affects fertility, and places significant psychological and physical stress on those infected. 

Unfortunately, there are a number of barriers to developing a vaccine. First, it’s hard to find people who are able to participate in the studies needed to test possible vaccines. Also, people who are infected may not have symptoms, which makes it more complicated to tell whether a vaccine is effective.

A Word From Verywell

Fortunately, you have other options for reducing the risk of transmission as research on herpes vaccines continues. Both suppressive therapy and reliably practicing safe sex can help protect the sexual partners of people with HSV infections.

Frequently Asked Questions

  • Does the herpes zoster vaccine protect you from genital herpes?

    No. The herpes zoster vaccine protects you against shingles (herpes zoster), a viral infection that is a reactivation of the chickenpox virus. There is currently no vaccine to protect against genital or oral herpes.

  • Is there a cure for oral or genital herpes?

    No. However, antiviral medications may prevent or reduce the severity of an oral or genital herpes outbreak. 

  • Can essential oils treat herpes?

    There is some evidence that certain types of oils can ease a herpes outbreak. For instance, oregano oil has been shown to have antiviral properties that act on HSV. But more research is needed to know if these will actually shorten an outbreak.

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16 Sources
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  1. Ghiasi H. Highly efficacious novel vaccine, humoral immunity, and ocular herpes simplex virus 1: reality or myth? J Virol. 2017;91(23). doi:10.1128/JVI.01421-17

  2. Crimi S, Florillo L, Bianchi A. et al. Herpes virus, oral clinical signs and QoL: systematic review of recent data. Viruses. 2019 May;11(5):463. doi:10.3390/v11050463

  3. Wang L, Zhu L, Zhu H. Efficacy of varicella (VZV) vaccination: an update for the clinician. Ther Adv Vaccines. 2016;4(1-2):20-31. doi:10.1177/2051013616655980

  4. Gabutti G, Bolognesi N, Sandri F, Flourescu C, Stefanati A. Varicella zoster virus vaccines: an update. Immunotargets Ther. 2019;8:15-28. doi:10.2147/ITT.S176383

  5. National Institutes of Health. Herpes can happen to anyone.

  6. Centers for Disease Control. Genital herpes - CDC fact sheet.

  7. Gottlieb SL, Giersing BK, Hickling J, et al. Meeting report: Initial World Health Organization consultation on herpes simplex virus (HSV) vaccine preferred product characteristics, March 2017. Vaccine. 2019;37(50):7408-7418. doi:10.1016/j.vaccine.2017.10.084

  8. Spicknall IH, Looker KJ, Gottlieb SL, et al. Review of mathematical models of HSV-2 vaccination: Implications for vaccine development. Vaccine. 2019;37(50):7396-7407. doi:10.1016/j.vaccine.2018.02.067

  9. Kuo T, Wang C, Badakshan T, Chilikuri S, BenMohamed L. The challenges and opportunities for development of a T-Cell epitope-based herpes simplex vaccine. Vaccine. 2014 Nov 28;32(50):6733-45. doi:10.1016/j.vaccine.2014.10.002

  10. Gottlieb SL, Johnston C. Future prospects for new vaccines against sexually transmitted infections. Curr Opin Infect Dis. 2017;30(1):77-86. doi:10.1097/QCO.0000000000000343

  11. Bernstein DI, Cardin RD, Smith GA, et al. The R2 non-neuroinvasive HSV-1 vaccine affords protection from genital HSV-2 infections in a guinea pig modelnpj Vaccines, 2020:5(1):104. doi:10.1038/s41541-020-00254-8

  12. Lopes PP, Todorov G, Pham TT, Nesburn AB, Bahraoui E, Benmohamed L. Laser adjuvant-assisted peptide vaccine promotes skin mobilization of dendritic cells and enhances protective CD8 T and T cell responses against herpesvirus infection and disease. J Virol. 2018;92(8). doi:10.1128/JVI.02156-17

  13. MedlinePlus. Genital herpes.

  14. FDA. Zostavax (Herpes Zoster Vaccine) Questions and Answers.

  15. Center for Disease Control and Prevention. Is there a Cure or Treatment for Herpes?

  16. Wang L, Wang D, Wu X, Xu R, Li Y. Antiviral mechanism of carvacrol on HSV-2 infectivity through inhibition of RIP3-mediated programmed cell necrosis pathway and ubiquitin-proteasome system in BSC-1 cells. BMC Infect Dis. 2020;20(1):832. doi:10.1186/s12879-020-05556-9

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