The study will evaluate the safety and immunogenicity of 3 consistency lots and a high-dose lot of rVSV-ZEBOV-GP (V920 Ebola Vaccine) in healthy adults. The primary purpose of this study is to demonstrate consistency in the immune responses of participants receiving 3 separate lots of V920 (at release dose) through 28 days postvaccination. A subset of participants representative of all treatment groups will continue through 24 months postvaccination in the extension study for the evaluation of safety, and durability of immune response. Safety of the vaccines and matching placebo will be evaluated through 6 months postvaccination for all participants and through 24 months postvaccination for participants continuing in the study extension.