FIRST-IN-MOP Project: Randomized, placebo-controlled trial to evaluate the safety, immunogenicity, and optimal dose of the Lassa fever vaccine candidate MOPEVAC-Las in healthy volunteers, comprising an open-label dose-escalation phase and a blinded treatment phase.

This page is intended for participants in the FIRST-IN-MOP study to find: Participation methods The latest news The overall results of the study as they become available New research using samples and data from participants in the FIRST-IN-MOP study Date of last update: 02/09/2026 What is the objective of the study? FIRST-IN-MOP is a clinical trial of a new Lassa fever vaccine. Lassa fever is a viral hemorrhagic fever present in West Africa, transmitted to humans by contact with rodents. Every year, epidemics cause hundreds of cases with a high risk of death (15 to 35%). Today, there is no effective treatment or vaccine against this disease. The objective of the FIRST-IN-MOP clinical trial is to evaluate the safety and tolerance of this new vaccine against Lassa fever, as well as its immunogenicity against this infection, that is to say its ability to trigger an immune response to fight the virus. If the safety and tolerance of this therapy are demonstrated, the benefit could be collective and the vaccine could benefit people at risk of being infected by Lassa fever. Who can participate? Healthy women and men aged between 18 and 55 years old and covered by a social security system are likely to be able to participate in the FIRST-IN-MOP study. What does participation in the study involve? Study participation will last a maximum of 14 months and will consist of 11 visits, including one screening visit, two vaccination visits and eight follow-up visits. News To come Overall results To come Outlook To come