The BD-Ebov trial is evaluating a new vaccine candidate designed to protect against Bundibugyo ebolavirus disease, a type of Ebola virus disease for which there are currently no licensed vaccines.
The sentinel phase is a standard safety step in vaccine clinical trials. It involves vaccinating a small number of participants first so that the study team, and an independent committee, can closely monitor safety before expanding recruitment to larger groups.
With this initial stage completed successfully, recruitment into the trial is continuing as planned.
The study is taking place against the backdrop of a rapidly evolving Bundibugyo virus disease outbreak in the Democratic Republic of the Congo, which has accelerated efforts to evaluate promising vaccine candidates.
It is now the largest Ebola outbreak ever reported in the Democratic Republic of the Congo (DRC), and the second largest outbreak ever globally. As of 5th August 2026, 3,973 confirmed cases, including 1,801 related deaths have been reported.
The BD-Ebov trial is being expedited to generate the data needed to determine whether the vaccine is safe and generates an immune response against Bundibugyo virus, with the ultimate aim of making it available to help protect communities affected by the current outbreak.
To mark this achievement, we spoke with Dr Peter Skidmore, the lead study doctor on the BD-Ebov trial, about what the completion of the sentinel group means, why this stage is so important, and what comes next for the study.
What happens after the sentinel phase has been completed?
The sentinel phase is designed to build safety into the trial from the very beginning. We vaccinated the first participant and then waited 48 hours before vaccinating the second and third participants. After a further 48 hours, the fourth and fifth participants were vaccinated. These planned intervals allowed the study team to carefully review the safety information from each group before moving on to vaccinate more volunteers.
Once all five participants in the sentinel group had been vaccinated, we continued to monitor them closely for a week, recording any side effects and carrying out regular safety assessments. An independent safety committee, completely separate from the Oxford Vaccine Group, then reviewed all of the data collected during this phase. Based on that review, the committee recommended that the trial should continue as planned, allowing recruitment into the next cohort to begin.
How are participants monitored following vaccination?
We ask participants to fill in a symptom diary online, where they can record if they have any of the side effects typically associated with vaccines, and also any unexpected side effects. Typically, the e-diary only takes around 5 minutes for the participant to fill in.
We also see participants in clinic a week after vaccination to check any side effects and do some safety blood tests. Participants have a phone number with 24/7 access to a doctor which they can call at any point if they are concerned about anything or want to ask questions.
Why is there still such an urgent need to develop vaccines against BDBV?
The BDBV outbreak in the DRC continues to spread and is now the second largest Ebola epidemic of all time. Whilst infection control and contact tracing measures continue to be vital, there are still no approved vaccines or medicines which can protect people against BDBV. Having these could help stop the outbreak sooner and save many lives.
Recruitment is continuing…. who can take part, and why is volunteer participation so important?
We are looking for healthy people aged between 18 and 55 who are able to come to regular visits at our site in Oxford. Our participants are the most important part of our trials, and our research couldn’t happen without them. We are hugely grateful to the people who kindly give up their time to help us protect the communities in DRC and elsewhere who are most at risk from Ebola outbreaks.
The BD-Ebov trial is continuing to recruit healthy adult volunteers. If you are interested in taking part or would like to learn more, visit our study website.