Phase 2
N=303
A Study of mRNA-1608, a Herpes Simplex Virus -2 (HSV-2) Therapeutic Candidate Vaccine, in Healthy Adults 18 to 55 Years of Age With Recurrent HSV-2 Genital Herpes
Genital Herpes
Bottom Line
View on ClinicalTrials.gov: NCT06033261 ↗Enrolled (actual)
303
Serious AEs
2.0%
Results posted
May 2026
Primary outcome: Primary: Number of Participants With Solicited Local and Systemic ARs — 74; 75; 75; 74 Participants
Study Design & Population
- Study type
- Interventional
- Phase
- Phase 2
- Interventions
- mRNA-1608 (Biological); BEXSERO (Biological)
- Age
- Adult · 18+ yrs
- Sex
- All
- Sponsor
- ModernaTX, Inc.
- Primary completion
- Apr 2025
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Number of Participants With Solicited Local and Systemic ARs |
74; 75; 75; 74 | — |
| PRIMARY Number of Participants With Unsolicited Adverse Events (AEs) |
22; 18; 18; 21 | — |
| PRIMARY Number of Participants With Serious Adverse Events (SAEs), Adverse Events of Special Interest (AESIs), and AEs Leading to Study Discontinuation |
0; 2; 2; 2; 0; 0 | — |
| PRIMARY Number of Participants With Medically Attended AEs (MAAEs) |
27; 22; 25; 26 | — |
| SECONDARY Number of Genital Herpes Recurrence Episode Per Participant, Counted Starting 14 Days After the Second Study Injection to 6 Months After Second Study Injection |
1.4; 1.2; 1.3; 1.0 | — |
| SECONDARY Number of Genital Herpes Recurrence Episode Per Participant, Counted Starting 14 Days After the Second Study Injection to 12 Months After Second Study Injection |
2.8; 2.3; 2.5; 1.8 | — |
| SECONDARY Change From Baseline (28 Days Prior to the First Study Injection) to 2 Months After the Second Study Injection in Genital Herpes Lesion Rate (Percentage of Days With Lesions Present) |
-7.75; -5.89; -10.70; -5.84 | — |
| SECONDARY Change From Baseline (28 Days Prior to the First Study Injection) to 6 Months After the Second Study Injection in Genital Herpes Lesion Rate (Percentage of Days With Lesions Present) |
-8.88; -5.40; -9.56; -6.73 | — |
| SECONDARY Change From Baseline (28 Days Prior to the First Study Injection) to 2 Months After the Second Study Injection in HSV-2 Genital Shedding Rate (Percentage of HSV-2 Deoxyribonucleic Acid [DNA] Positive Anogenital Swabs) |
-2.08; -2.06; -4.63; -1.36 | — |
| SECONDARY Change From Baseline (28 Days Prior to the First Study Injection) to 6 Months After the Second Study Injection in HSV-2 Genital Shedding Rate (Percentage of HSV-2 DNA Positive Anogenital Swabs) |
-2.72; -3.36; -7.62; -0.69 | — |
| SECONDARY Geometric Mean (GM) Value of mRNA-1608 Antigen-Specific Binding Antibodies (bAbs) |
1096279.5; 1983151.9; 2625389.8; 2611517.7; 1082161.1; 1442891.5 | — |
| SECONDARY Geometric Mean Fold Rise (GMFR) of mRNA-1608 Antigen-Specific bAbs |
1.05; 2.57; 2.95; 3.03; 1.02; 1.83 | — |
| SECONDARY Percentage of Participants With Vaccine Seroresponse |
1.5; 15.9; 27.8; 26.2; 2.9; 85.5 | — |
Summary
The purpose of this study is to generate safety and immunogenicity data and establish a proof-of-concept of clinical benefit of the mRNA-1608 vaccine candidate.
Eligibility Criteria
Inclusion Criteria
- Participant has a diagnosis of genital HSV-2 infection for at least 1 year before the Screening Visit.
- Seropositive for HSV-2 as determined by Western Blot.
- Participant has a history of recurrent genital herpes defined as at least 3 and no more than 9 reported genital herpes recurrences in the 12 months preceding the Screening Visit, or if currently on suppressive therapy, prior to initiation of suppressive therapy.
- Willing to refrain from taking suppressive antiviral therapy from the Screening Visit until the end of the study.
- Willing to refrain from the use of episodic antiviral therapy during the three 28-day anogenital swabbing periods. Episodic therapy may be used outside the three 28-day swabbing periods.
- For female participants of childbearing potential: negative pregnancy test, adequate contraception, and not currently breastfeeding.
Exclusion Criteria
- Prior immunization with a vaccine containing HSV antigens.
- History of any form of ocular HSV infection, HSV-related erythema multiforme, or HSV-related neurological complications.
- History of genital HSV-1 infection.
- History of hepatitis B, hepatitis C, or human immunodeficiency virus (HIV) types 1 or 2 (HIV-1, HIV-2).
- Reported history of anaphylaxis or severe hypersensitivity reaction after receipt of any mRNA vaccine(s) or any components of the mRNA vaccines.
- Previously received BEXSERO or other vaccine to prevent serogroup B meningococcal disease (also known as meningitis B).
- History of allergic disease or reactions likely to be exacerbated by any component of BEXSERO vaccine.
- Has received or plans to receive any licensed or authorized vaccine, including COVID-19 vaccines, ≤ 28 days prior to the first study injection (Day 1), or plans to receive a licensed or authorized vaccine within 28 days before or after study injection with the exception of licensed influenza vaccines, which may be received more than 14 days before or after any study injection.
Note: Other inclusion and exclusion criteria may apply.
Data sourced from ClinicalTrials.gov (NCT06033261). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.