The goal of this clinical trial is to assess the safety and immunogenicity of a self-replicating (sr) RNA-based vaccine, JCXH-105, in the prevention of Shingles (Herpes Zoster)

Participant will be randomized to receive either JCXH-105 or Shingrix.

This Phase 1 study plans to enroll a total of 75 participants.

Three cohorts with 3 different dose levels of JCXH-105 will be explored and each cohort will enroll 25 participants (20 randomized to JCXH-105 and 5 randomized to Shingrix) for a total of 75 participants. The dose level of JCXH-105 will depend on the time the participant joins the study. Each participant will receive two single intramuscular (IM) injections of study treatment (JCXH-105 or Shingrix) on day 1 and day 61 (±2 days on day 61)

Inclusion Criteria:

• Sex: Male or female; female subjects may be of childbearing potential, of nonchildbearing potential, or postmenopausal.
• Age: 50 to 69 years of age, inclusive, at screening.
• Status: Healthy subjects. Note: Healthy status as defined by the absence of evidence of any clinically significant active or chronic disease, in the opinion of the Investigator, following a detailed medical and surgical history, a complete physical examination including vital signs, 12-lead electrocardiogram (ECG) recording, hematology, blood chemistry, serology, and urinalysis. Healthy subjects may have stable pre-existing disease defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 6 weeks prior to enrollment.
• Subjects must agree to not be vaccinated with any HZ vaccine while participating in this study.
• All values for hematology and clinical chemistry tests of blood and urine within the normal range OR showing no clinically relevant deviations based on medical history, considering stable pre-existing diseases (see Healthy Subjects above), as judged by the Investigator.

Exclusion Criteria:

• Subjects with a history of HZ or current diagnosis of shingles.
• Previous vaccination against HZ.
• Subjects with any respiratory illness deemed clinically relevant by the Investigator within the past month OR hospitalization >24 hours for any reason within the past month prior to the first vaccine administration (JCXH-105 or Shingrix).
• Subjects with history of myocarditis or pericarditis, or with AEs after mRNA vaccination that are in nature and severity beyond the common expected AEs necessitating medical intervention.
• Subjects who have received an mRNA-based vaccine (e.g., Spikevax, Comirnaty, etc.) 30 days prior to Day 1.
• Subjects who received any non-live vaccine within 14 days prior to the first vaccine administration (JCXH-105 or Shingrix).
• Subjects who received within 28 days prior to first vaccine administration (JCXH-105 or Shingrix): (1) Any live vaccine, (2) Immunomodulators or immune-suppressive medication, (3) Granulocyte-macrophage colony-stimulating factor, (4) Three or more consecutive days of systemic corticosteroids. Note: subjects on stable-dose steroid replacement (for chronic disease such as iatrogenic deficiency) of prednisone ≤10 mg/day or equivalent are allowed, and (5) Other investigational agents or devices.
• Subjects with active or suspected immunosuppression, immunodeficiency, or autoimmune disease.
• Subjects receiving systemic antiviral therapy.
• Subjects with a positive screening test for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies, or anti-human HIV-1 and 2 antibodies.
• Subjects with a positive screening test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
• Subjects with a known history of active or latent tuberculosis (bacillus tuberculosis).

Double blinded study