Phase IIa Pilot Study Evaluating the Efficacy of a Monoclonal Antibody and Vaccine-based Post-exposure Prophylaxis Strategy in High-risk Contact Cases of Ebola Virus Disease Infection

• Three measures are currently being implemented to control Ebola outbreaks:

• Monitoring of contacts

• Isolation and treatment of sick people

• Vaccination of the population in high-risk areas.

• In contacts with high viral exposure and therefore a high risk of incubation and rapid expression of infection, the r-VSV-ZEBOV vaccine does not provide adequate protection because vaccine antibody production is effective 6 to 10 days after administration.

• Specific monoclonal antibodies (Mab) from the Regeneron and mAb114 research specialties have been shown to be effective in reducing mortality in patients with Ebola virus disease (EVD).

• Their use in a single parenteral administration and good tolerability make them candidates for use in post-exposure prophylaxis (PEP) in individuals at high risk of viral exposure.

• A comprehensive strategy for the protection of high-risk contacts must therefore be implemented, including the vaccine and the Mabs, to ensure both immediate and prolonged protection. Indeed, the efficacy of the vaccine is likely to be diminished when co-administered with Mabs, as both strategies share the same viral target (the GP envelope glycoprotein) and the vaccine is replicative (and therefore may be inhibited by Mabs).

PROVAE aim to evaluate the effectiveness of a comprehensive strategy to prevent transmission of MVE in contacts at high risk of infection, including (i) post-exposure prophylaxis with Mabs and (ii) vaccination with r-VSV-ZEBOV.