Safety and immunogenicity of rVSVΔG-ZEBOV-GP vaccination when dosed concurrent with mRNA COVID-19 vaccine booster doses in healthy African adults (EbolaCov): protocol for a phase IV, single-centre, single-blinded, randomised controlled trial.

Publication date: Sep 21, 2025

Ebola virus disease remains a significant public health concern. For protection from Ebola virus, the main target populations are epidemiologically identified and often include healthcare workers and refugees. These target populations are also routinely offered vaccines for other vaccine-preventable diseases. However, concomitant use of rVSVΔG-ZEBOV-GP with other vaccines is not recommended, given the absence of data regarding its reactogenicity and antigen-specific immunogenicity profile when co-administered. The EbolaCov trial aims to inform whether rVSVΔG-ZEBOV-GP can be administered concurrent to a Pfizer-BioNTech COVID-19 booster dose without an unacceptable increase in reactogenicity and/or loss of humoral immunogenicity to Ebola vaccine antigen. This is a single-centre, randomised, single-blinded, vaccine safety and immunogenicity study in healthy adults living in Rwanda. Seventy-two participants will be randomised in a 1:1 ratio to two study groups, the first receiving rVSVΔG-ZEBOV-GP with a placebo, the second group receiving rVSVΔG-ZEBOV-GP concurrently with a Pfizer-BioNTech COVID-19 booster dose. The primary outcome measures are quantitative serum anti-glycoprotein (GP) antibody responses, as measured by ELISA, 28 days after vaccination, and frequency and severity of adverse events in the 7 days following vaccination. Secondary outcome measures include day 28 and day 180 serum anti-GP and serum SARS-CoV-2 anti-spike protein-specific geometric mean antibody titres. This trial was approved by the Rwanda National Ethics Committee (reference 442/2024) and the University of Birmingham (reference ERN_2661-Jun2024). All participants were required to provide written informed consent in accordance with good clinical practice. Dissemination of results will be through conference presentations and peer-reviewed publications. Pan African Clinical Trials Registry (PACTR202407764378004) and ClinicalTrials. gov (NCT06587503).

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