A Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of Cytomegalovirus (CMV) Vaccine mRNA-1647

Exclusion Criteria

• •History of a diagnosis or condition that, in the judgment of the investigator, is clinically unstable or may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to study procedures. Clinically unstable is defined as a diagnosis or condition requiring significant changes in management or medication within the 2 months prior to screening and includes ongoing workup of an undiagnosed illness that could lead to a new diagnosis or condition.
• •Participant has elevated liver function tests, defined as aspartate aminotransferase (AST), alanine aminotransferase (ALT), or alkaline phosphatase (ALP), or elevated creatinine or reduced platelets, with a toxicity score of Grade ≥1 at screening.
• •Participant has laboratory test results (hematology, chemistry, and coagulation) with a toxicity score of Grade ≥1 at screening.
• •Received or plans to receive any non-study vaccine \<28 days prior to any study injection; in addition, the following criteria for COVID-19 and influenza vaccines apply:
• •i. Any COVID-19 vaccination series must have been completed a minimum of 28 days prior to receiving any dose of the study injection.
• •ii. COVID-19 vaccines (regardless of manufacturer) must be administered at least 28 days prior to or after any study injection.
• •iii. Influenza vaccines may be administered \>14 days prior to or after any study injection.
• •Participant has received systemic immunosuppressants or immune-modifying drugs for \>14 days in total within 6 months before the day of first injection (Day 1) (for corticosteroids, \>5 mg/day of prednisone equivalent) or plans to do so during the course of the study. Inhaled, nasal, and topical steroids are allowed.
• •Participant has received an antiviral with activity against CMV (ganciclovir, valganciclovir, foscarnet, cidofovir, letermovir, acyclovir, valacyclovir) within 2 weeks before the first injection or plans to do so during the course of the study.
• •Participant received any investigational CMV vaccine.
• •History of myocarditis, pericarditis, or myopericarditis.
• •Reported medical history of hepatitis B, hepatitis C, or human immunodeficiency virus (HIV); or a positive screening test for hepatitis B surface antigen (HbSAg), hepatitis C antibodies, or HIV 1 or 2 antibodies.