STRIVE (Sierra Leone Trial to Introduce a Vaccine Against Ebola)

The Ebola outbreak was confirmed in March 2014 with widespread and intense transmission in Guinea, Liberia, and Sierra Leone. While there are no U.S. Food and Drug Administration (FDA)-approved pharmaceuticals to prevent or treat Ebola, two candidate vaccines are being tested in humans for dosing, tolerability, and safety. This study will evaluate monovalent recombinant vesicular stomatitis virus Ebola vaccine that remains replication competent (rVSVΔG-ZEBOV) in Sierra Leone. The high infectivity of blood and secretions, lack of appropriate personal protective equipment (PPE) and challenges in following infection control and prevention protocols put healthcare workers at high risk during outbreaks, and direct contact with the bodies of deceased Ebola victims can also sustain community transmission. This unblinded, randomized trial will evaluate vaccine efficacy (VE) and safety with phased vaccine introduction in the target population. Participation in the study will be voluntary and open to adults 18 years of age and older who are at high risk of exposure to Ebola infection through their daily work and who work in a selected study area. This includes: 1) personnel working in healthcare facilities where care is provided for Ebola patients; 2) personnel working in non-Ebola healthcare facilities who may have exposure to undiagnosed Ebola-infected individuals; and 3) personnel working in one of the following job categories: surveillance team, ambulance team, or laboratory worker responsible for swabbing deceased persons. Staff members involved in this study are also eligible to receive the vaccine under this protocol; study staff will be followed for 6 months post-vaccination to monitor for safety of rVSVΔG-ZEBOV. Eligible participants within a healthcare facility or frontline team will be enrolled and individually randomized to either immediate or deferred vaccination. A single dose of rVSVΔG-ZEBOV will be administered intramuscularly. Immediate vaccination is defined as vaccination within 7 days of enrollment and deferred vaccination is defined as vaccination at the end of an 18-24 week follow-up period. Participants will not be blinded to the randomized assignment of immediate or deferred vaccination. All enrolled participants will have the opportunity to receive rVSVΔG-ZEBOV by the end of the study. Enrollment and vaccination will be phased over time. Ebola events that occur during the 18-24 week post-enrollment will be included in the VE analysis, with the immediate vaccination arm contributing vaccinated follow-up time and the deferred vaccination arm contributing unvaccinated follow-up time. All participants, regardless of randomized assignment, will be followed for 6 months after vaccination to monitor for safety of rVSVΔG-ZEBOV.