Evaluating Safety and Immune Response of Ervebo and Zabdeno Booster Vaccines in Adults Previously Vaccinated Against Ebola Virus in DRC A Phase 3 Randomized Controlled Trial

What this Trial Is About

Researchers are investigating whether adults in the Democratic Republic of Congo who were previously vaccinated against Ebola virus with either the ZabdenoMvabea4 or Ervebo4 vaccine schedules can be safely and effectively boosted using either the same homologous or a different heterologous vaccine schedule. This randomized controlled trial aims to compare immune responses and safety profiles between these booster approaches, hypothesizing that heterologous boosters will produce similar antibody and cellular responses without added safety concerns. The study includes 624 participants divided into two groups based on their initial vaccination 312 with ZabdenoMvabea4 and 312 with Ervebo4. Each group is further randomized to receive either a single intramuscular booster of the same vaccine or the alternate one, resulting in four study arms. Booster doses are given once, with doses of 0.5 ml for Zabdeno4 and 1 ml for Ervebo4. Blood samples will be collected at multiple pre-set visits over six months to measure antibody levels and cellular immune responses. An additional 50 non-vaccinated participants will be enrolled to assist in laboratory assay optimization. Participants will attend clinic visits at specific times during the six-month follow-up to provide blood samples and undergo safety assessments, including monitoring for adverse events and vital signs. The study will evaluate antibody levels 21 days after booster vaccination as the primary outcome, along with various secondary measures of immune response and safety checks at several timepoints. Safety and tolerability will be closely recorded, and participant medical history and medication use will be reviewed to understand factors influencing vaccine response.

Safety and Immunogenicity of Ervebo® and Zabdeno® Booster Vaccines Against Ebola Virus Following Previous Vaccination with the Zabdeno/Mvabea® or Ervebo® Vaccine Schedules in DRC