HerpesVaccinations.com

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.

HerpV phase 2
Agenus · protein subunit · HSV-2 · therapeutic

HerpV (formerly AG-707) is a therapeutic HSV-2 vaccine candidate made of synthetic HSV-2 peptides complexed with a human heat shock protein, which a 2024 review describes as a subunit vaccine from Agenus. A Phase I study in HSV-2-infected participants reported it was well tolerated and produced T cell responses; an Agenus-sponsored Phase 2a trial on viral shedding in 80 adults with recurrent genital herpes was completed in 2015. As of the 2026-09-27 registry search, no record naming HerpV has an ongoing status, and a 2024 review states the program has not advanced further.
VCL-HB01 phase 2
Vical · DNA · HSV-2 · therapeutic

VCL-HB01 is a therapeutic HSV-2 DNA vaccine sponsored by Vical, tested in adults who already have symptomatic HSV-2 infection. It was studied in a phase 1/2 dose-escalation trial with 165 actual enrolments, completed in 2016, and a phase 2 trial with 261 actual enrolments, completed in 2018. Neither trial has results posted on the registry, and as of the 2026-09-27 registry search no record naming VCL-HB01 has an ongoing status.
G103 phase 1
Sanofi Pasteur, a Sanofi Company (lead sponsor of NCT04222985) · protein subunit · HSV-2 · therapeutic

G103 is an investigational therapeutic vaccine for genital herpes made of three recombinant HSV-2 proteins. A 2025 report describes a randomized, placebo-controlled trial of G103 in combinations with the replication-defective vaccine HSV529 in 24 participants, reporting adequate safety profiles and increases in T cell and antibody responses. The registry search returned one record, the Sanofi Phase 1 trial NCT04222985, which does not name G103 and was terminated for business reasons; as of 2026-09-28, no record has an ongoing status.
HSV529 phase 1
Sanofi Pasteur (trials run with NIAID and Fred Hutchinson Cancer Center) · replication-defective live · HSV-2 · both

A replication-defective whole-virus HSV-2 vaccine that has been tested in three Phase 1 trials, in people with and without existing herpes infection. In the first trial it was safe and raised neutralizing antibodies in most vaccinated people who had never been infected, but not in people who already had HSV. No efficacy trial has been run, and no HSV529 trial is currently active.
BCHT HSV-2 mRNA vaccine phase 1
Changchun BCHT Biotechnology Co. · mRNA · HSV-2 · unclear

This is an mRNA vaccine against HSV-2 whose registered trial is sponsored by Changchun BCHT Biotechnology Co. Its phase 1 dose-escalation trial, NCT07330440, is evaluating safety, tolerability and immunogenicity in healthy participants aged 18-55, stratified by serostatus. As of the 2026-09-27 registry search, that trial was the one record found and was enrolling by invitation, with no results posted.
GSK4108771A phase 1
GlaxoSmithKline · other · unclear · unclear

GSK4108771A is an HSV vaccine sponsored by GlaxoSmithKline, registered in a phase 1 dose-escalation trial in healthy adults aged 18-40. That trial, the registry record that names GSK4108771A, was terminated in 2021 after 17 actual enrolments, to enable development of an enhanced version of the vaccine, and has no results posted. A separate GSK phase 1/2 trial of an HSV-targeted immunotherapy completed in 2025; its registry listing describes "HSV formulation" arms rather than naming GSK4108771A, so whether it tests the same vaccine is unconfirmed.

See all 13 candidates in the full tracker →

Common questions about herpes vaccines

Short, neutral answers to the questions people most often ask — each links to a page on this site where the claim is sourced and dated.

Is there a herpes vaccine?
No herpes (HSV) vaccine is approved anywhere as of 2026. Several candidates have entered or completed early-stage human trials, but none has been shown to prevent or treat herpes in the way needed for approval. See the candidate tracker →
Is a herpes vaccine coming in 2026?
There is no approved herpes vaccine and no announced approval date. The programs with trials still under way are in early-phase (Phase 1) testing, and a trial existing is not evidence that it will succeed. We do not predict timelines. See how far each candidate has reached → Why an early-phase trial is not an approval →
Which herpes vaccines are in development?
Programs with a trial currently listed as ongoing include BioNTech's BNT163, a preventive mRNA candidate in Phase 1, and an mRNA vaccine from Changchun BCHT in Phase 1. Earlier programs include therapeutic candidates that completed Phase 2 trials, such as Agenus's HerpV and Vical's VCL-HB01, as well as Moderna's mRNA-1608 (discontinued in November 2025), GSK's Herpevac and Genocea's GEN-003. Full tracker with sources → BNT163 → The BCHT mRNA vaccine →
What is the difference between HSV-1 and HSV-2?
HSV-1 has traditionally caused oral herpes and HSV-2 genital herpes, but either type can infect either site. The distinction matters for vaccines: a candidate can protect against one type and not the other. HSV-1 vs HSV-2 explainer →
What is the difference between a preventive and a therapeutic herpes vaccine?
A prophylactic (preventive) vaccine aims to stop an uninfected person from getting HSV. A therapeutic vaccine is for people already infected, to reduce outbreaks and shedding. They use different trials, endpoints, and populations, and a candidate can target one goal and not the other. Prophylactic vs therapeutic explainer →
Why isn't there a herpes vaccine yet?
HSV establishes lifelong latency in nerve cells and evades parts of the immune response, which makes it a hard vaccine target. Several approaches have reached human trials; none has yet cleared the bar for approval. Why HSV is hard to vaccinate against → What clearing each trial phase would take →

Latest updates

Dated notes on new developments — trial read-outs, results, and status changes. A trial starting is not evidence it will succeed.

  • 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.

See all updates →

Explainers

Plain-language background on the science behind HSV vaccine research — sourced and dated, like everything else here.

  • How mRNA herpes vaccines work

    Several of the most-watched herpes vaccine candidates use mRNA — the same technology behind the COVID-19 vaccines. This explainer covers how an mRNA vaccine delivers instructions for a cell to make selected viral proteins, why several HSV programs chose the approach, and why a platform that works for one disease is not proof it will work for another.

  • 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.

See all explainers →

Latest research

Key papers and trial reports behind these candidates — each labeled with its publication status and linked to its source with a neutral summary.

See all research →