This clinical study will evaluate the safety, reactogenicity, and immunogenicity of monovalent mRNA-1982, a messenger ribonucleic acid (mRNA) vaccine to prevent Lyme disease in healthy adults aged 18 to 70 years old.

Key Inclusion Criteria:

• In good general health in the opinion of the investigator as determined by medical evaluation including medical history and physical examination at screening.
• Contraceptive use by participants should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

Key Exclusion Criteria:

• History of anaphylaxis or severe hypersensitivity reaction requiring medical intervention after receipt of any mRNA vaccine or therapeutic or any components of an mRNA vaccine or therapeutic.
• Have chronic illness related to Lyme disease or an active symptomatic Lyme disease infection as suspected or diagnosed by a physician.
• Received treatment for Lyme disease within the prior 3 months.
• Previously vaccinated against Lyme disease or participated in the past in any vaccine study for Lyme disease.
• Had a tick bite within 4 weeks prior to Day 1.

Note: Additional inclusion/exclusion criteria may apply, per protocol.