This is a randomized, active-controlled, dose-escalation multi-center study of 2 doses (Day 1 and Week 8) of an investigational herpes zoster (HZ) vaccine (Z-1018), combining herpes zoster antigen- (gE) with a Toll-like receptor 9 (TLR9) agonist adjuvant (CpG 1018) with and without alum in approximately 150 healthy volunteers 50 to 69 years of age (inclusive).

Inclusion Criteria:

• Male or female, 50 to 69 years of age
• Be in good health in the opinion of the investigator, based upon medical history, physical examination, and laboratory evaluation
• Must be able to comprehend and follow all required study procedures and be available for all visits scheduled in the study
• Seronegative for human immunodeficiency virus (HIV)

Exclusion Criteria:

• History of HZ

• Previous vaccination against varicella or HZ

• If female of childbearing potential, is pregnant, breastfeeding, or planning a pregnancy

• Known history of HIV (HIV 1/2 antibodies)

• Has a history of sensitivity to any component of study vaccines

• Has received any blood products or immunoglobulin within 90 days prior to study injection, or is likely to require infusion of blood products during the study period

• Has received the following prior to the first injection:

  • 14 days: any non-live vaccine
  • 28 days:
  • Any live vaccine, including a COVID-19 vaccine
  • Systemic corticosteroids (more than 3 consecutive days) or other immunomodulators or immune suppressive medication, with the exception of inhaled steroids
  • Granulocyte or granulocyte-macrophage colony-stimulating factor
  • Any other investigational medicinal agent, including a COVID-19 vaccine

• Chronic administration of immunosuppressants or other immune-modifying drugs within 6 months prior to the first vaccine dose

• Is undergoing chemotherapy or expected to receive chemotherapy during the study period; has a diagnosis of cancer within the last 5 years other than squamous cell or basal cell carcinoma of the skin

• History or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the study, interfere with the subject's participation for the full duration of the study, or is not in the best interest of the subject to participate, in the opinion of the treating investigator

• History of autoimmune disease