A Trial to Evaluate Safety, Tolerability, and Immune Responses of an Investigational Monovalent Chimpanzee Adenoviral Vectored Marburg Virus Vaccine in Healthy Adults

This is a multi-center, double-blinded, placebo-controlled, Phase 2 study to evaluate safety, tolerability, and immunogenicity of a single dose of cAd3-Marburg Vaccine in healthy adults 18 to 70 years of age, in a US-based population. The study will enroll 200 eligible participants randomized 4:1 to receive the cAd3-Marburg Vaccine at 1.0 × 10\^11 PU/dose or placebo (normal saline; 0.9% sodium chloride (NaCl) solution for injection) at Day 1, intramuscularly, in deltoid muscle. Participants will be screened for eligibility up to 28 days before enrollment. Safety data will be periodically reviewed by an independent DSMB. Safety and immunogenicity will be assessed at Days 1, 8, 15, 29, 85, 169, and will conclude at the end of study visit on Day 366. PBMCs will be collected from a subset of 40 subjects on days 1, 15, 29, 169 and will conclude at the end of study visit on Day366 to access cellular immunity. All participants will also be contacted telephonically on Days 4 and 42 (unless a clinic visit is medically indicated, or participant does not have a phone contact) for safety follow-up.