A Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of mRNA-1468 in Healthy Adults ≥50 Years of Age

Inclusion Criteria:

• Part 1: Is an adult 50 years of age or older at the time of consent. Part 2: Is anadult 50-69 years of age at the time of consent.

• Has a body mass index of 18 to <40 kilograms/meter squared at the Screening Visit.

• Females of childbearing potential: have a negative pregnancy test at the ScreeningVisit and on the day of the first vaccination (Day 1); have practiced adequatecontraception or has abstained from all activities that could result in pregnancyfor at least 28 days prior to Day 1; have agreed to continue adequate contraceptionthrough 3 months following vaccine administration; are not currently breastfeeding.

Exclusion Criteria:

• Has a history of HZ within the past 10 years.

• Has been previously vaccinated against varicella or HZ.

• Is acutely ill or febrile

• Body temperature ≥38.0°Celsius/100.4°Fahrenheit 72 hours prior to or at theScreening Visit or on Day 1. Participants meeting this criterion may be rescheduledwithin the allowed window.

• Has a current or previous diagnosis of congenital or acquired immunodeficiency,immunocompromizing/immunosuppressive condition, asplenia, or recurrent severeinfections. Certain immune-mediated conditions that are well controlled and stable (for example, Hashimoto thyroiditis) as well as those that do not require systemicimmunosuppressive therapy (for example, asthma, psoriasis, or vitiligo) may bepermitted at the discretion of the Investigator.

• Has a dermatologic condition that could affect local solicited adverse reactionassessments (for example, tattoos, psoriasis patches affecting skin over the deltoidareas).

• Has any medical, psychiatric, or occupational condition, including reported historyof substance abuse, that, in the opinion of the Investigator, might pose additionalrisk due to participation in the study or could interfere with the interpretation ofstudy results.

• Has a history of myocarditis, pericarditis, or myopericarditis.

• Has a reported history of anaphylaxis or severe hypersensitivity reaction afterreceipt of any mRNA vaccine(s) or any components of the mRNA vaccines.

• Has received systemic immunosuppressants for >14 days in total within 180 days priorto Screening Visit (for corticosteroids ≥10 milligrams/day of prednisone orequivalent) or is anticipating the need for systemic immunosuppressive treatment atany time during participation in the study. Inhaled, nasal, intra-articular andtopical steroids are allowed.

• Has received systemic immunoglobulins, long-acting biological therapies that affectimmune responses (for example, Infliximab) or blood products within 90 days prior tothe Screening Visit or plans to receive them during the study.

Other protocol-defined inclusion/exclusion criteria apply.