Herpes Vaccines December 2025
Developing protective vaccines against the herpes simplex virus (HSV) has been a longstanding challenge in clinical trials. Current herpes vaccine candidates are based on DNA, modified mRNA, subunit, killed-virus, and attenuated-live-virus technologies. As of December 29, 2025, the U.S. Food and Drug Administration (FDA), Brazil, Canada, China, the European Union, India, Japan, and the United Kingdom had not authorized preventive or therapeutic vaccines for herpes simplex virus types 1 (HSV-1) or 2 (HSV-2).
The World Health Organization (WHO) published its preferred product characteristics for Alpha (α)-herpesviruses vaccines and updated its pipeline review in late 2024. In coordination with its Global Health Sector Strategy on HIV, viral hepatitis, and sexually transmitted infections for 2022-2030, the WHO works to increase awareness about genital herpes infections and related symptoms. The WHO, the U.S. National Instuties of Health (NIH), and global partners launched STI Watch, a portal containing updated information on vaccine development status. Both preventive and therapeutic HSV vaccines are being explored.
As of December 2025, herpes vaccine and antiviral candidates conducting clinical trials include:
Assembly Biosciences ABI-5366 is an advanced helicase primase inhibitor targeting people with HSV-2 With Recurrent Genital Herpes. The Phase 1a/1b clinical trial (NCT06385327, ABI-5366-101) found that ABI-5366 was well-tolerated and presented a pharmacological profile supporting potential once-weekly or even once-monthly dosing. The October 2025 oral presentation titled "Safety, pharmacokinetics and antiviral activity of ABI-5366: interim data from a phase 1b study" highlights positive interim data from the first two cohorts of participants with recurrent genital herpes. Gilead Sciences, Inc. announced on December 22, 2025, that it exercised its combined option to exclusively license Assembly Bio's herpes simplex virus (HSV) helicase-primase inhibitor programs, including long-acting investigational candidates ABI-1179 and ABI-5366 for recurrent genital herpes.
mRNA-1608 is an mRNA vaccine candidate against HSV-2 disease. The mRNA-1608-P101 Phase 1 study was launched on September 6, 2023, and is expected to be completed on June 4, 2025. With mRNA-1608, Moderna Inc. aims to induce a strong antibody response with neutralizing and effector functionality combined with cell-mediated immunity—Independent Study: An mRNA vaccine to prevent genital herpes.
BNT163 is an mRNA-based HSV vaccine candidate that encodes three HSV-2 glycoproteins. These glycoproteins help prevent HSV from entering and spreading within cells and counteract HSV's immunosuppressive properties.
RatioVaccines' VC2 vaccine candidate is a live-attenuated vaccine targeting facial, ocular, and genital herpes caused by HSV-1 and may also protect against genital herpes caused by HSV-2. On October 13, 2023, Rational Vaccines was awarded $2.8 million by the U.S. National Institutes of Health. In 2018, a study conducted at Louisiana State University, Brent Stanfield and colleagues examined the immune response generated by the intramuscular injection of the VC2 vaccine in guinea pigs.
Delta gD-2 (∆gD-2) is a vaccine candidate based on an HSV-2 virus genetically deleting glycoprotein D (gD-2).
HSV529 (HSV15) is a replication-defective vaccine candidate. This means the virus possesses all components of the wild-type HSV, except for two proteins, UL5 and UL29, which are involved in viral DNA replication. Sanofi Pasteur and the National Institute of Allergy and Infectious Diseases last updated this phase 1/2 study on January 13, 2021.
EXD-12 is a vaccine candidate currently tested for safety and efficacy as a prophylactic and therapeutic vaccine against herpes simplex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2).
NanoVax is an adjuvant platform to develop a vaccine candidate to protect against the two viruses that can cause genital herpes.
RVx201 is a live-attenuated HSV-2 vaccine candidate conducting an observational clinical study, RVx-001-PSS, in England. It is designed to achieve a specific degree of attenuation through mutations engineered into the ICP0 protein.
Shanghai BD Gene is conducting a phase 1/2 clinical study in humans. It is the only gene-editing technology for Cas9 mRNA delivery by lentivirus.
Assembly Biosciences, Inc. announced data from development candidate ABI-5366, a long-acting HSV helicase inhibitor targeting high-recurrence genital herpes.
A research study published on May 28, 2024, highlights the potential of an effective combination therapy using the two monoclonal anti-gB IgGs (HDIT101 and HDIT102) for the treatment of HSV-1 and HSV infections.
GSK plc announced on September 11, 2024, that it had completed the primary objective data analysis from the phase II part of the TH HSV REC-003 trial for GSK3943104, a therapeutic HSV vaccine candidate. The results show that GSK3943104 did not meet the study's primary efficacy objective. Therefore, this vaccine candidate will not progress to phase III studies.
Redbiotec is developing an HSV-2 therapeutic vaccine, also known as immunotherapy. Their vaccine program uses T-cell-mediated protection and aims to outperform antivirals. With two injections, patients can remain symptom-free for over 12 months.
Eurocine vaccine candidates against HSV-2—In a non-human study, mRNA vaccination stimulated potent T cell responses that significantly outcompeted those generated by the protein vaccine in performance in several specific areas. Dr. Karl Ljungberg, Director of Preclinical Development at Eurocine Vaccines, stated in December 2022, "The T cell responses that we report here align with those that can be detected after recovery from an infection and are focused on the part of the HSV-2 virus that we believe is important to target to obtain immunologic control of the virus."
Researchers designed and constructed an HSV-1 synthetic platform based on the H129 Strain of G4. This platform could facilitate further manipulation of the HSV-1 genome, the development of neuronal circuit tracers, oncolytic viruses, and vaccines.
A January 2025 study reviewed the development and characterization of the vaccine potential of replication-competent controlled herpesviruses, representing the first examples of regulated microbes used as vaccines.
The journal MDPI published an article on July 18, 2023, that concluded B7 costimulation molecules expressed from a replication-defective vaccine can enhance vaccine efficacy, even in an immunocompetent host.
Herpes Vaccine Candidate Clinical Trials
When developing herpes vaccines, participants are selected for clinical trials in phases 1, 2, 3, and 4. Each development phase is essential. Herpes Cure Advocacy launched Herpes Cure Pipeline 2.0 in March 2022, which tracks the timelines and strategies of preclinical and clinical studies. The Vaccine Value Profile (VVP) for HSV aims to provide a comprehensive, high-level assessment of the information and data currently available to inform the potential public health, economic, and societal value of pipeline vaccines and vaccine-like products.
Herpes Vaccine News
A study published in 2024 showed that the economic costs of genital herpes infections amount to an estimated $35 billion a year worldwide through healthcare expenditures and productivity loss. To confirm HSV infections, commercial labs offer confidential testing services in 2025.