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

Inclusion Criteria:

• Participant has a diagnosis of genital HSV-2 infection for at least 1 year beforethe 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 nomore than 9 reported genital herpes recurrences in the 12 months preceding theScreening Visit, or if currently on suppressive therapy, prior to initiation ofsuppressive therapy.

• Willing to refrain from taking suppressive antiviral therapy from the ScreeningVisit 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, adequatecontraception, 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, orHSV-related neurological complications.

• History of genital HSV-1 infection.

• History of hepatitis B, hepatitis C, or human immunodeficiency virus (HIV) types 1or 2 (HIV-1, HIV-2).

• Reported history of anaphylaxis or severe hypersensitivity reaction after receipt ofany mRNA vaccine(s) or any components of the mRNA vaccines.

• Previously received BEXSERO or other vaccine to prevent serogroup B meningococcaldisease (also known as meningitis B).

• History of allergic disease or reactions likely to be exacerbated by any componentof BEXSERO vaccine.

• Has received or plans to receive any licensed or authorized vaccine, includingCOVID-19 vaccines, ≤ 28 days prior to the first study injection (Day 1), or plans toreceive a licensed or authorized vaccine within 28 days before or after studyinjection with the exception of licensed influenza vaccines, which may be receivedmore than 14 days before or after any study injection.

Note: Other inclusion and exclusion criteria may apply.