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

Solicited ARs were collected in an electronic diary (eDiary). Local ARs: injection site pain, erythema (redness), swelling/induration (hardness); and axillary (underarm) swelling or tenderness ipsilateral to the side of injection. Systemic ARs: fever, headache, fatigue, myalgia, arthralgia, nausea/vomiting, and chills. Note, not all solicited ARs were considered adverse events (AEs). Investigator reviewed whether the solicited AR was also to be recorded as an AE. A Summary of serious AEs (SAEs) and nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.

An AE was defined as any untoward medical occurrence associated with the use of a drug in humans, whether or not considered drug related. Any abnormal laboratory test result (hematology, clinical chemistry, or prothrombin time [PT]/partial thromboplastin time [PTT]) or other safety assessment (for example, electrocardiogram, radiological scan, vital sign measurement), including one that worsened from baseline and was considered clinically significant in the medical and scientific judgment of the Investigator was recorded as an AE. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.

An SAE was defined as any AE that resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in disability, was a congenital anomaly/birth defect, or was an important medical event. An AESI was an AE (serious or nonserious) of scientific and medical concern specific to the Sponsor's product or program, for which ongoing monitoring and immediate notification by the Investigator to the Sponsor were required. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.

A MAAE is an AE that led to an unscheduled visit to a healthcare practitioner. A summary of SAEs and all nonserious AEs ("Other"), regardless of causality, is located in the "Reported Adverse Events" section.

An episode of recurrence was defined as one or more consecutive "yes" to the "Do you have genital herpes lesion?" question either from Genital Herpes Signs and Symptoms (GHSS) or daily recurrence eDiary within a 14-day period from the first "yes" response regardless of "no" or missing entries in between. The start date of an episode was the first date of "yes" response, and the end date of an episode was the last date of "yes" within the episode. The recurrence analysis period up to 6 months included the time from 14 days after the second injection until the last GHSS or daily recurrence eDiary collected up to the 1) the Day 225 visit date or 2) if Day 225 visit date is not available, the earliest of study Day 225 or study discontinuation date.

An episode of recurrence was defined as one or more consecutive "yes" to the "Do you have genital herpes lesion?" question either from GHSS or daily recurrence eDiary within a 14-day period from the first "yes" response regardless of "no" or missing entries in between. The start date of an episode was the first date of "yes" response, and the end date of an episode was the last date of "yes" within the episode. The recurrence analysis period up to 12 months included the time from 14 days after the second injection until the last GHSS or daily recurrence eDiary collected up to the 1) the Day 393 visit date or 2) if Day 393 visit date is not available, the earliest of study Day 393 or study discontinuation date.

Genital herpes lesion rate was defined for each 28-day swabbing period as the number of days with lesion present according to the eDiary divided by the number of days during the 28-day swabbing period.

Genital herpes lesion rate was defined for each 28-day swabbing period as the number of days with lesion present according to the eDiary divided by the number of days during the 28-day swabbing period.

Genital shedding rate was defined for each 28-day swabbing period as the number of anogenital swabs with HSV-2 DNA positive results (that is, positive results per polymerase chain reaction [PCR]) divided by the number of swabs during the swabbing period.

Genital shedding rate was defined for each 28-day swabbing period as the number of anogenital swabs with HSV-2 DNA positive results (that is, positive results per PCR) divided by the number of swabs during the swabbing period.

Antibody values reported as below the lower limit of quantification (LLOQ) were replaced by 0.5 * LLOQ. Values greater than the upper limit of quantification (ULOQ) were replaced by the ULOQ if actual values were not available. LLOQ was 1220 units (U)/milliliter (mL) and ULOQ was 6890000 U/mL for HSV2 gB. LLOQ was 1230 U/mL and ULOQ was 21300000 U/mL for HSV2 gC. LLOQ was 2220 U/mL and ULOQ was 23900000 U/mL for HSV2 gD. 95% confidence interval (CI) was calculated based on the t-distribution of the log-transformed values for GM, then back transformed to the original scale for presentation.

Antibody values reported as below the LLOQ were replaced by 0.5 * LLOQ. Values greater than the ULOQ were replaced by the ULOQ if actual values were not available. LLOQ was 1220 U/mL and ULOQ was 6890000 U/mL for HSV2 gB. LLOQ was 1230 U/mL and ULOQ was 21300000 U/mL for HSV2 gC. LLOQ was 2220 U/mL and ULOQ was 23900000 U/mL for HSV2 gD. 95% CI was calculated based on the t-distribution of the difference in the log-transformed values for GMFR, then back transformed to the original scale for presentation.

Seroresponse was defined as a change from baseline below the LLOQ to equal or above 4 * LLOQ, or at least a 4-fold rise if baseline was equal to or above the LLOQ. LLOQ was 1220 U/mL and ULOQ was 6890000 U/mL for HSV2 gB. LLOQ was 1230 U/mL and ULOQ was 21300000 U/mL for HSV2 gC. LLOQ was 2220 U/mL and ULOQ was 23900000 U/mL for HSV2 gD. 95% CI was calculated using the Clopper-Pearson method.