A Study of an Epstein-Barr Virus (EBV) Candidate Vaccine, mRNA-1195, in 18- to 55-Year-Old Healthy Participants

Key Inclusion Criteria: * For Part A: Positive EBV serostatus at Screening. For Part B: Negative EBV serostatus or Positive EBV serostatus at Screening. * According to the assessment of the Investigator, is in good general health and can comply with study procedures. * For participants of childbearing potential: negative pregnancy test, adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to Day 1, agreement to continue adequate contraception through 3 months following last study injection and is not currently breast/chest feeding. Key Exclusion Criteria: * Participant is acutely ill or febrile (temperature ≥38.0 degrees Celsius \[°C\]/100.4 degrees Fahrenheit \[°F\]) 72 hours prior to or at the Screening Visit or Day 1. * Symptomatic acute or chronic illness requiring ongoing medical or surgical care, to include changes in medication in the past 2 months indicating that chronic illness/disease is not stable (at the discretion of the Investigator). * Any medical, psychiatric, or occupational condition, including reported history of drug or alcohol abuse, that, in the opinion of the Investigator, might pose additional risk due to participation in the study or could interfere with the interpretation of study results. * History of myocarditis, pericarditis, or myopericarditis. * Participant has received systemic immunosuppressants or immune-modifying drugs for \>14 days in total within 6 months prior to Screenin…