New mRNA vaccine shows promise against common virus that can harm newborns

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Male or female 18-40 years of age (Part 1); Female 18-40 years of age (Part 2) * Understands and agrees to comply with the trial procedures and provides written informed consent * According to the assessment of the Investigator, is in good general health and is capable of complying with trial procedures * Body mass index (BMI) 18-35 kilograms/meter (kg/m\^2) * Female participants must either be of non-childbearing potential or use acceptable methods of contraception from at least 28 days prior to the first vaccination and through 3 months following last vaccination and is not breastfeeding. * Male participants must agree to practice adequate contraception from the time of the first vaccination and through 3 months after the last vaccination. Exclusion Criteria: * Acutely ill or febrile on the day of the first vaccination * Prior receipt of any CMV vaccine * Abnormal screening safety laboratory test results * Diagnosis or condition that, in the judgment of Investigator, is clinically unstable or may affect participant safety, assessment of safety endpoints, assessment of immune response, or adherence to trial procedures * Has received or plans to receive a vaccine ≤28 days prior to the first vaccination or plans to receive a non-study vaccine within 28 days prior to or after any study vaccination, except for any licensed influenza vaccine which can be administered \>14 days before or after any study vaccination. COVID-19 vaccines (regardless of manufacturer) may be administered \>7 days but preferably \>14 days before or after any study vaccination, with the intention of prioritizing COVID-19 vaccination over all other considerations. * Prior receipt of chronic systemic immunosuppressants or immune-modifying drugs * Receipt of intravenous immunoglobulins or plasma products within 3 months prior to the day of the first study vaccination * Previous receipt of medications in lipid nanoparticle (LNP) formulation (Part 1 participants only) * Has donated ≥450 milliliters (mL) of blood products within 28 days of the Screening visit * Participated in an interventional clinical trial within 28 days prior to the day of enrollment * Is an immediate family member or household member of trial personnel