This is a randomized, double-blind, placebo-controlled Phase 1 study of the safety and immunogenicity of AVX601 vaccine at two dosage levels and two routes of administration in healthy volunteers conducted at a single research center. A total of 40 participants will be enrolled into two groups of 20 participants each. Within each group, participants will be randomized to receive the active vaccine by IM injection (N = 8) or SC injection (N = 8) or to receive a placebo by IM injection (N = 2) or SC injection (N = 2). Each participant will receive a total of six injections of vaccine or placebo, two at each visit at Weeks 0, 8 and 24, administered by a study nurse in an outpatient setting, and will be followed for 12 months after the first immunization. Safety data will include local and systemic reactogenicity after each dose of vaccine, collected in a systematic format using a subject memory aid and a standard grading scale, specific safety laboratory parameters and general AEs. Immunogenicity data will be obtained by collecting blood at defined time points before and after immunization and separating serum (for measurement of antibodies to CMV by ELISA and neutralization assays and to the vaccine vector by a VRP neutralization assay) and peripheral blood mononuclear cells (PMBC) (for measurement of cellular immune responses to CMV peptides).