The purpose of this study is to evaluate the safety and immunogenicity of two Ebola virus disease (EVD) vaccines, Ad26.ZEBOV (rHAd26) and rVSVΔG-ZEBOV-GP (rVSV), in children and adults. These vaccines will be studied using three different strategies: the rHAd26 vaccine plus a MVA-BN-Filo (MVA) boost, and the rVSV vaccine with or without boosting.~Participants will be randomized into five groups: the Ad26.ZEBOV vaccine with an MVA boost, the rVSV vaccine with or without boosting, or one of two placebo groups. At Day 0 (study entry), participants will receive the Ad26.ZEBOV vaccine, the rVSV vaccine, or placebo.~At Day 56, participants assigned to the rVSV vaccine without a boost and the two placebo groups will receive placebo. Those initially given the Ad26.ZEBOV vaccine will receive the MVA boost. Those assigned to the boosted rVSV group will receive the rVSV boost.~Additional study visits will occur on Days 7, 14, 28, and 63, and at Months 3, 6, 12, 24, 36, 48, and 60. Study visits may include blood collection and other assessments.~Some participants may take part in substudies, which will include blood or saliva collection.~After the Month 12 visit, during the long-term follow-up, the participants who received the placebo will be vaccinated with a single dose of rVSVΔG-ZEBOV-GP vaccine in Liberia and Mali and with the Ad26.ZEBOV/MVA-BN-Filo vaccine strategy in Guinea and Sierra Leone. The participants who received an incomplete Ad26.ZEBOV/MVA-BN-Filo vaccine strategy will be offered a single dose of the Ad26.ZEBOV or MVA-BN-Filo vaccine in Guinea and Sierra Leone and a single dose of rVSVΔG-ZEBOV-GP in Liberia and Mali.
The purpose of this study is to evaluate the safety and immunogenicity of three vaccine strategies that may prevent Ebola virus disease (EVD) events in children and adults. Participants will receive either the Ad26.ZEBOV (rHAd26) vaccine with a MVA-BN-Filo (MVA) boost, or the rVSVΔG-ZEBOV-GP (rVSV) vaccine with or without boosting, or placebo.