A Phase 2 Study to Evaluate JCXH-105, an srRNA-based Herpes Zoster Vaccine

Key Inclusion Criteria: * Sex: Male or female; female subjects may be of childbearing potential, of nonchildbearing potential, or postmenopausal. * Age: ≥ 50 years of age at screening. * Status: Healthy subjects. * Subjects must agree to not be vaccinated with any HZ vaccine while participating in this study. * Subjects must agree to not be vaccinated with any RNA-based vaccines (e.g., Spikevax, Comirnaty, etc.) 30 days before Dose 1 through 30 days after Dose 2 (a 4-month period). Key Exclusion Criteria: * Subjects with a history of HZ within the past 10 years or current diagnosis of HZ. * 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 who are acutely ill or febrile with body temperature ≥ 38.0º Celsius/100.4º Fahrenheit 72 hours prior to or at the Screening visit or on Day 1 pre-dose. Subjects meeting this criterion may be rescheduled within an allowable window with approval from the Sponsor. * Subjects with history or current diagnosis of congenital or acquired immunodeficiency/immunocompromising/immunosuppressive conditions, asplenia, or recurrent severe infections. Certain immune-mediated conditions (e.g., Hashimoto thyroiditis) that are well controlled and stable are allowed. * Subjects with history of myocarditis or pericarditis, or with AEs (including anaphylaxis and severe hypersensitivity) after mRNA vaccination that are in nature and severity beyond the common expected AEs and necessitating medical intervention. * Subjects who received any non-live vaccine within 14 days prior to Day 1 (first dose of JCXH-105 or Shingrix). * Subjects who received within 28 days prior to Day 1 (first dose of JCXH-105 or Shingrix): (1) Any live vaccine, (2) Immunomodulators or immune-suppressive medication, (3) Granulocyte or 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 receiving systemic antiviral therapy. * Subjects with a positive screening test for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies, anti-human HIV-1 and 2 antibodies, or syphilis. * Subjects with a positive screening test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).