Moderna, Inc. announced the first participant has been dosed in the Phase 3 pivotal registration study of mRNA-1647, the Company?s cytomegalovirus (CMV) vaccine candidate. This study is known as CMVictory. CMV is a latent virus that remains in the body for life after infection. In adults, initial infection with CMV often goes undetected. The CDC estimates that over half of adults are infected by age 40. For most healthy individuals, CMV does not pose a long-term health risk, but it can lead to lifelong medical conditions. For some, including those with weakened immune systems or infants born with CMV infection, it can have serious consequences. A pregnant mother with an active CMV infection may pass the virus to her unborn child, resulting in congenital CMV infection. Although most infants with congenital CMV appear normal at birth, approximately 1 in 5 will have long-term health problems such as hearing loss, vision impairment, learning disabilities and decreased muscle strength and coordination. Some newborns with congenital CMV appear very ill at birth with jaundice, rash, liver and spleen enlargement, and seizures. Congenital CMV is the leading infectious cause of birth defects in the United States. Moderna?s mRNA vaccine portfolio includes candidates against respiratory viruses, candidates against tropical viruses, and candidates against latent viruses. Latent viruses remain in the body for life after infection. mRNA-1647 is the Company?s first attempt to help protect people from latent virus infection with a vaccine. Moderna is also advancing vaccine candidates against other latent viruses including Epsten-Barr virus (EBV) and human immunodeficiency virus (HIV). EBV is a member of the herpesvirus family that includes CMV, herpes simplex virus (HSV), and varicella-zoster virus (VZV). EBV is spread through bodily fluids (e.g., saliva) and contracted primarily by young children and adolescents. It is a major cause of infectious mononucleosis (IM) and associated risks to other long-term medical conditions including an increased risk of developing multiple sclerosis by approximately 4 to 10-fold, certain lymphoproliferative disorders and cancers and autoimmune diseases. HIV is the virus responsible for acquired immunodeficiency syndrome (AIDS), a lifelong, progressive illness with no effective cure. Worldwide, approximately 38 million are currently living with HIV; including approximately 1.2 million in the U.S. Approximately 2 million new infections are acquired worldwide each year, and approximately 690,000 of those people die. Moderna?s vaccine candidate against CMV, mRNA-1647, combines six mRNAs in one vaccine, which encode for two proteins located on the surface of CMV: five mRNAs encoding the subunits that form the membrane-bound pentamer complex and one mRNA encoding the full-length membrane-bound glycoprotein B (gB). Both the pentamer and gB are essential for CMV to infect barrier epithelial surfaces and gain access to the body, which is the first step in CMV infection. mRNA-1647 is designed to produce an immune response against both the pentamer and gB for the prevention of CMV infection. Currently, there is no approved vaccine to prevent CMV. Phase 1 and 2 studies of mRNA-1647 demonstrated functional antigen-specific responses that support the vaccine candidate?s potential to prevent CMV infection. Interim, seven-month data from the Phase 2 study of mRNA-1647 at the 50 ?g, 100 ?g and 150 ?g dose levels showed that mRNA-1647 was generally well tolerated. Based on the interim analysis of the Phase 2 study, the 100 ?g dose was chosen for the Phase 3 study. The Phase 3 study, known as CMVictory, will evaluate the safety and efficacy of mRNA-1647 against primary CMV infection in women ages 16-40 years. The Company will seek to enroll approximately 8,000 participants in the study, including 6,900 women of childbearing age, from approximately 150 sites globally, beginning in the U.S.Moderna has set a goal of enrolling a diverse group of U.S. participants into the study, including approximately 42% of participants who are Persons of Color. The ClinicalTrials.gov identifier is NCT05085366.