This is a randomized, observer-blind, placebo-controlled, parallel-group, multicenter, Phase 2 study evaluating the safety, tolerability and immunogenicity of 2-dose heterologous regimens using Ad26.ZEBOV and MVA-BN-Filo administered to healthy adults participants in Europe. The study involves a screening period of up to 12 weeks, a vaccination period in which participants will be vaccinated with Ad26.ZEBOV (dose 1) followed by vaccination with MVA-BN-Filo (dose 2) 28, 56 or 84 days later, and a post-vaccination phase until 6 months post dose 2 visit (Days 209, 237 or 265). After unblinding, only participants who received Ad26.ZEBOV and/or MVA-BN-Filo will continue the study until the Day 365 visit (or until the start of the roll-over study or for an additional 12 months [whichever comes first] for participants in France who agree to continue the long-term follow-up after Day 365) to assess long-term safety and immunogenicity. Participants will enroll into 3 cohorts: that is, Cohort 1 (Participants will receive Ad26.ZEBOV and MVA-BN-Filo in an open-label fashion), Cohort 2 (Participants will be randomized to receive the 2-dose heterologous vaccine regimen with either Ad26.ZEBOV followed by MVA-BN-Filo, or placebo in a 14:1 ratio) and Cohort 3 (Participants will be randomized to receive the 2-dose heterologous vaccine regimen with either Ad26.ZEBOV followed by MVA-BN-Filo, or placebo in a 10:3 ratio). In Cohorts 2 and 3, core immunogenicity assessments (humoral and cellular assays) will be performed. In Cohort 2, additional immunogenicity assessments will be done. In Cohort 1, plasma blast response kinetics will be evaluated. Safety will be monitored during the study.
The purpose of this study is to evaluate the safety, tolerability, and immunogenicity of 3 vaccination schedules of Ad26.ZEBOV and MVA-BN-Filo administered intramuscularly (IM) as 2-dose heterologous regimens.