Ebola Clinical Trials Launched in DRC: Two Studies Test the First Potential Treatments and a Prophylaxis for the Bundibugyo Strain

For the first time, clinical trials are underway in the Democratic Republic of the Congo (DRC) to find treatments specifically targeting the rare Bundibugyo strain of Ebola, a virus for which no licensed vaccine or drug exists. The two parallel studies — the EBO-PEP trial for post-exposure prophylaxis and the PARTNERS trial for treatment — represent a critical international effort to curb a fast-growing outbreak that has already killed hundreds.

The Outbreak and the Urgent Need for Treatments

The current outbreak of Bundibugyo virus disease (BVD), caused by the species Orthoebolavirus bundibugyoense, was first confirmed in the DRC on May 15, 2026 . It quickly spread to neighboring Uganda . As of July 14, 2026, the European Centre for Disease Prevention and Control (ECDC) reported 1,963 confirmed cases and 719 deaths in the DRC (data through July 12), and 736 confirmed cases and 246 deaths in Uganda (as of July 15) .

The outbreak is centered in the Ituri province of northeastern DRC, with cases also reported in North Kivu and South Kivu provinces . Unlike the more common Zaire ebolavirus, for which effective vaccines (like Ervebo) and antibody treatments (like Inmazeb and Ebanga) are licensed, the Bundibugyo strain has no such medical countermeasures . This dire gap, combined with the virus's rapid spread and cross-border transmission, led the World Health Organization (WHO) to declare the outbreak a Public Health Emergency of International Concern (PHEIC) on May 17, 2026 .

The EBO-PEP Trial: Testing an Oral Pill to Prevent Infection

The EBO-PEP trial is the first clinical study to evaluate an oral antiviral, obeldesivir (ODV), as post-exposure prophylaxis (PEP) for people who have had high-risk contact with a confirmed Bundibugyo case but are not yet sick .

• Drug: Obeldesivir, an experimental oral antiviral developed by Gilead Sciences . In nonhuman primate studies, it has shown 80–100% protection against lethal Ebola virus infection when given 24 hours after mucosal exposure, and complete protection against Sudan virus .
• Sponsor: Gilead Sciences .
• Implementing partners: The National Institute for Biomedical Research (INRB) in Kinshasa, ANRS Emerging Infectious Diseases / Inserm, and the NGO ALIMA .
• Launch date: First participants enrolled on July 14, 2026 .
• Location: Ituri province, DRC, the epicenter of the outbreak .
• Study design: A placebo-controlled randomized trial targeting high-risk contacts of confirmed Bundibugyo cases. Researchers aim to enroll nearly 1,000 participants, recruiting them outside Ebola treatment centers .
• Patient eligibility: High-risk contacts of confirmed Bundibugyo Ebola cases who are within the window for post-exposure prophylaxis .

The PARTNERS Trial: Testing Remdesivir and MBP134 for Treatment

The PARTNERS (Platform Adaptive Randomised Trial for New and Repurposed Filovirus TreatmentS) trial is designed to identify effective treatments for people already diagnosed with Bundibugyo virus disease .

• Drugs tested: Remdesivir (Gilead's broad-spectrum antiviral) and MBP134 (Mapp Biopharmaceutical's monoclonal antibody cocktail), tested alone and in combination .
• Sponsor: Coordinated by the World Health Organization (WHO) .
• Launch date: First patient enrolled on July 2, 2026 .
• Location: Bunia, Ituri province, DRC, at the Evangelical Medical Center .
• Study design: An adaptive, multi-arm randomized trial enrolling up to ~1,200 patients to evaluate whether remdesivir, MBP134, or their combination can reduce mortality from BVD compared to standard supportive care . Patients will be randomized to receive one of the drugs, a combination, or standard care . The U.S. government and Gilead Sciences donated all doses for the trial .

A Critical Gap: No Licensed Vaccines or Treatments for Bundibugyo

The central reason these trials were urgently launched is that all existing Ebola vaccines and antibody therapies are strain-specific. The licensed Ervebo vaccine and the antibody treatments Inmazeb and Ebanga are effective only against the Zaire ebolavirus . For the Bundibugyo strain, there are currently no approved vaccines or therapeutics . This was underscored by the WHO when it first recommended the evaluation of obeldesivir as a PEP candidate in May 2026 . The European Medicines Agency (EMA) has also identified obeldesivir, remdesivir, and MBP134 as promising candidates for clinical trials in this outbreak .

The outcome of the EBO-PEP and PARTNERS trials will determine whether the global health community finally has tools to treat and prevent this historically neglected but lethal strain of Ebola.