Where each herpes vaccine candidate actually stands
A neutral, evidence-first tracker of herpes-simplex-virus (HSV) vaccine research. Every status claim is sourced and dated. We do not sell anything, promise timelines, or promote any candidate.
BioNTech's mRNA prophylactic (preventive) vaccine candidate aimed at preventing genital lesions caused by HSV-2, and potentially HSV-1. Its first-in-human Phase 1 trial began in December 2022 and is ongoing but no longer recruiting, with estimated primary completion in October 2026. As of mid-2026 it is an early-stage safety and immune-response study; no efficacy results have been published.
A therapeutic protein-subunit vaccine from Genocea Biosciences for people already infected with HSV-2. In Phase 2 trials it reduced viral shedding and genital-lesion rates for up to 12 months. Despite these results, Genocea halted the program in 2017 to pivot to cancer immunotherapy, and it has not been revived by any developer since.
A prophylactic protein-subunit vaccine from GlaxoSmithKline built around HSV-2 glycoprotein D. In a large Phase 3 trial published in 2012, it failed to prevent genital disease caused by HSV-2 — its intended target — but unexpectedly reduced HSV-1 genital disease by about 58%. This HSV-1 versus HSV-2 split became an influential lesson in the field. The program was not taken further.
Moderna's mRNA therapeutic vaccine candidate for people who already have recurrent HSV-2 genital herpes. Its Phase 1/2 trial completed in April 2025 and reported encouraging interim safety, immune-response, and exploratory clinical-endpoint data. In November 2025 Moderna discontinued the program as part of a broader pipeline prioritization; it will not proceed to Phase 3.
This is a documented cautionary case, not a live vaccine candidate. Theravax (and its preventive counterpart Profavax) was a live-attenuated herpes vaccine promoted by Rational Vaccines and researcher William Halford. It was given to about 20 people in 2016 in an offshore trial on St. Kitts that had no institutional review board approval and no FDA oversight — later the subject of an FDA criminal investigation and university findings of serious noncompliance. No credible efficacy evidence exists, and the program is defunct. It is listed here so readers can recognize why it is not a legitimate option.
An academic mRNA vaccine from the University of Pennsylvania (Harvey Friedman and Drew Weissman) that targets three HSV-2 glycoproteins — gC2, gD2, and gE2. It has shown strong protection against genital herpes in animal models but has not itself been tested in a registered human trial. Penn licensed the technology to BioNTech, whose Phase 1 candidate BNT163 is the clinical form of this approach.
See all 6 candidates in the full tracker →
Latest updates
- New preclinical data extend the trivalent mRNA approach to HSV-1 eye disease
A peer-reviewed mouse study from the University of Pennsylvania group behind the trivalent gC2/gD2/gE2 mRNA design — the approach licensed to BioNTech as BNT163 — reported that the vaccine protected against HSV-1 eye infection and spread to the nervous system in mice. The findings are preclinical (in animals) and broaden the trivalent rationale beyond genital HSV-2; on their own they are not evidence of protection in people.
- Moderna ends its therapeutic HSV vaccine program (mRNA-1608)
Moderna announced on 20 November 2025 that it will not advance mRNA-1608, its therapeutic HSV-2 vaccine candidate, to Phase 3, discontinuing the program as part of a company-wide pipeline prioritization. Its Phase 1/2 trial had completed in April 2025 with encouraging interim data; the available reporting frames the decision as strategic rather than a reported safety or efficacy failure.
- IDWeek 2025: first clinical data for two mRNA HSV vaccine candidates
At IDWeek 2025 (19–22 October, Atlanta), interim clinical data were presented for two mRNA herpes vaccine candidates: BioNTech's prophylactic BNT163 (Phase 1) and Moderna's therapeutic mRNA-1608 (Phase 1/2). Both are early-stage safety and immune-response read-outs shared as conference abstracts — encouraging early signals, not evidence that either prevents or controls disease.
Explainers
- HSV-1 vs HSV-2: what's the difference?
Herpes simplex virus comes in two types. HSV-1 has traditionally caused oral herpes and HSV-2 genital herpes, but that line has blurred, and either type can infect either site. The distinction still matters for vaccines: a vaccine can protect against one type and not the other, as the Phase 3 Herpevac trial showed. Neither type has an approved vaccine as of 2026.
- Prophylactic vs therapeutic: two very different herpes vaccines
"A herpes vaccine" can mean two different things. A prophylactic (preventive) vaccine is given to people who are not infected, to stop them getting herpes simplex virus (HSV) at all. A therapeutic vaccine is given to people who are already infected, to reduce outbreaks and viral shedding. The two use different trials, endpoints, and populations — so the first question to ask of any candidate is which goal it targets. Neither type is approved.
- What each clinical trial phase does and doesn't prove
A plain-language guide to reading herpes (HSV) vaccine news by trial phase. Each phase answers a different question, and early-phase results say nothing about whether a vaccine prevents disease. A trial existing or finishing is not the same as a vaccine working — the Phase 3 Herpevac trial ran to completion but missed its main goal, and as of 2026 no HSV vaccine has cleared Phase 3 to approval.
Latest research
- Immunogenicity and Efficacy of a Trivalent HSV-2 gC2, gD2, gE2 Nucleoside-Modified mRNA-LNP Vaccine Against HSV-1 Eye Infection and Neuroinvasion in Mice
- Safety and Immunogenicity of BNT163, a Trivalent mRNA HSV Vaccine Candidate for Genital Herpes
- mRNA-1608, an mRNA-Based Therapeutic Genital Herpes Vaccine Candidate: Interim Safety, Immunogenicity and Clinical Endpoint Results from a Phase 1/2 Trial