Researchers in the Democratic Republic of Congo have started enrolling participants in a trial evaluating Gilead Sciences’ experimental antiviral obeldesivir as a post-exposure treatment for the ongoing Bundibugyo Ebola outbreak in the Democratic Republic of Congo and Uganda.
The trial is being led by Congo’s National Institute for Biomedical Research and France’s ANRS Emerging Infectious Diseases, with support from Alliance for International Medical Action (ALIMA) and Médecins Sans Frontières. According to a joint statement, the study is being conducted in Ituri province, the epicentre of the outbreak.
The trial is designed to assess whether post-exposure treatment can reduce the risk of developing Ebola infection after contact with the virus. Researchers aim to enroll about 1,000 people aged 12 years and older who had high-risk exposure to a confirmed Ebola case within the previous five days and who have not developed symptoms.
Participants will be monitored daily for 21 days, followed by a final follow-up assessment at 42 days. Obeldesivir has shown activity against filoviruses, including the Bundibugyo Ebola virus, in pre-clinical studies.
Gilead has donated 2,400 bottles of obeldesivir and 2,000 vials of remdesivir to support the trial. Initial funding includes 3.4 million euros ($3.87 million) from the Global Health EDCTP3 partnership supported by the European Commission and $1 million from the Africa Centres for Disease Control and Prevention (Africa CDC). Africa CDC also helped secure an additional $5 million in funding commitments from South Africa and the Democratic Republic of Congo.
The study includes a separate compassionate-use protocol under which Gilead’s injectable antiviral remdesivir will be provided to children under 12 years of age and to pregnant or breastfeeding women who have been exposed to the virus.
According to government data, the outbreak has resulted in 1,963 confirmed cases in Congo, including 719 deaths.
Alongside the antiviral study, the first vaccine against the Bundibugyo Ebola virus is preparing to enter a Phase 1 clinical trial. The study will be conducted in the United Kingdom and will assess the safety and immune response of the vaccine candidate, ChAdOx1 BDBV, in 50 healthy adults aged 18 to 55 years. Recruitment is underway, and the first participants are expected to be vaccinated in the coming weeks following regulatory review.
The ChAdOx1 BDBV vaccine was developed by the University of Oxford’s Oxford Vaccine Group in collaboration with the Serum Institute of India using the same platform as the AstraZeneca COVID-19 vaccine.
Nicole Lurie, M.D., CEPI Executive Director Preparedness and Response, said, “Every step brings a safe and effective vaccine closer and helps strengthen our ability to protect vulnerable communities, save lives, and bring this outbreak under control”.
Since the outbreak was declared on May 15 and spread across the Democratic Republic of Congo and Uganda, efforts have focused on vaccine development and clinical testing. CEPI launched an $8.6 million partnership with the University of Oxford and the Serum Institute to advance vaccine development.
The Serum Institute has supplied 4,000 investigational doses of the ChAdOx1 BDBV vaccine for the Phase 1 trial and has 620,000 additional doses stored for future use. If the Phase 1 trial is successful, CEPI plans to support late-stage trials aimed at generating data for emergency approval and licensure.
CEPI has also established collaborations with Merck & Co., Moderna, and the International AIDS Vaccine Initiative (IAVI) to advance additional vaccine candidates into clinical trials. More recently, Merck Chief Medical Officer Eliav Barr told Reuters that the company is considering making Lagevrio, an antiviral pill used for emergency purposes during the COVID pandemic, available as an Ebola treatment.
Obeldesivir has entered a new phase of clinical evaluation as researchers begin a trial to assess its effectiveness against Bundibugyo Ebola, a less common but serious strain of the Ebola virus. The study aims to determine whether Obeldesivir can safely reduce viral replication, improve patient outcomes, and provide healthcare professionals with an effective antiviral treatment during future outbreaks.
As Ebola outbreaks continue to pose a global health threat, the development of targeted antiviral therapies remains a high priority. The latest trial represents another important milestone in expanding treatment options beyond supportive care.
Why the Obeldesivir Trial Matters
The new Obeldesivir clinical trial focuses on patients infected with the Bundibugyo strain of Ebola virus. Researchers will evaluate the drug’s safety profile, antiviral activity, and its ability to shorten recovery time while reducing severe complications.
The development of Obeldesivir highlights continued investment in antiviral research for emerging infectious diseases. Successful outcomes may strengthen global preparedness efforts, improve treatment availability, and provide clinicians with an additional evidence-based therapy for Ebola virus disease.
While the trial is still underway, healthcare experts remain optimistic that Obeldesivir could contribute to more effective management of future Bundibugyo Ebola outbreaks.
