A Study to Investigate The Safety, Tolerability, And Immune Response of a Range of Doses of mRNA-1769 Compared With Placebo in Healthy Participants From ≥18 Years of Age to <50 Years of Age

Inclusion Criteria: * Has a body mass index (BMI) between ≥18 kilogram per square meter (kg/m\^2) to ≤39 kg/m\^2. * For female participants of childbearing potential: must have a negative highly sensitive pregnancy test with 28 days before the first dose of study drug, uses approved contraception during the study intervention period and for at least 3 months after the last dose of study drug, and not currently breastfeeding. Exclusion Criteria: * History of smallpox vaccination, vaccination with any poxvirus-based vaccine, history of of/or recent exposure to Mpox (MPX) (defined as close contact with a confirmed case of MPX within the past 14 days). * Participant should not have any significant, progressive, unstable, or uncontrolled clinical condition, including any condition that may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures per Investigator judgement. * Participant is undergoing investigations for a potential chronic medical disorder. * Bleeding disorder considered a contraindication to IM injection or phlebotomy. * Dermatologic conditions that could affect local solicited AR assessments. * History of anaphylactic reaction or allergic reactions that required medical intervention following any vaccine. * Known or suspected allergy to any component of mRNA-1769. * History of malignancy within previous 10 years (excluding non-melanoma skin cancer). * Participant has any medical, psychiatric, or…