Researchers in Uganda have begun a Phase I clinical trial of an experimental vaccine targeting the Bundibugyo strain of Ebola, as health authorities intensify efforts to respond to an outbreak spreading in the Democratic Republic of the Congo (DRC).
The first participants received doses of the candidate vaccine on October 6 in Masaka, southwestern Uganda, in a study led by the Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, in partnership with the University of Oxford.
The vaccine, known as ChAdOx1 BDBV, was developed by Oxford scientists to protect against Bundibugyo ebolavirus, a strain for which no licensed vaccine is currently available. The trial is part of an international effort to develop protection against Ebola virus species not covered by existing licensed vaccines.
The Uganda study aims to recruit 110 healthy adult volunteers aged 18 to 55. Researchers will assess the vaccine’s safety and tolerability, as well as whether it stimulates an appropriate immune response.
Participants will be monitored for 12 months, allowing researchers to assess potential side effects and measure immune responses over time. The study includes a randomised, placebo-controlled group and additional groups receiving the candidate vaccine under different vaccination schedules.
Phase I trials are an early stage of clinical research. Their primary purpose is to determine whether a candidate vaccine can be administered safely and to gather preliminary evidence of its ability to trigger an immune response. They are not designed to establish conclusively whether a vaccine prevents infection or stops an outbreak.
The Uganda trial follows an initial first-in-human study of the same vaccine candidate in the United Kingdom, also supported by the Coalition for Epidemic Preparedness Innovations (CEPI).
The research comes amid a major Ebola outbreak in eastern DRC, where Bundibugyo ebolavirus has spread across several provinces. Health authorities have faced challenges associated with limited medical resources, insecurity and difficulties reaching affected communities.
The outbreak has renewed concern about the lack of licensed vaccines and specific treatments for the Bundibugyo strain, increasing the urgency of research into new preventive tools.
An existing Ebola vaccine, Ervebo, is effective against the Zaire strain but is not established as protection against Bundibugyo ebolavirus. Researchers in the DRC are also preparing studies to evaluate whether the existing vaccine offers any protection against the strain responsible for the current outbreak.
The Uganda study is supported by CEPI as part of a broader programme to advance the candidate vaccine. The Serum Institute of India has worked with Oxford on manufacturing and preparing doses for clinical development, including supplies for the Uganda and UK studies.
Researchers say the trial could provide important evidence for future outbreak preparedness. However, further clinical studies will be needed before the vaccine can be considered for wider use, and its effectiveness against Bundibugyo infection has not yet been established.
The trial represents a step towards addressing a significant gap in Ebola prevention. Its results will help determine whether the vaccine can progress through subsequent stages of testing and potentially become a tool for protecting communities affected by future outbreaks.
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