FACTBOX: What Bundibugyo Ebola vaccines and treatments are under development

Global health authorities are accelerating efforts to identify medical countermeasures to contain an outbreak of Bundibugyo ebolavirus in eastern Democratic Republic of Congo.

Unlike the more commonly studied Zaire strain of Ebola, there are currently no approved vaccines or treatments specifically for Bundibugyo ebolavirus (BDBV). The outbreak has already resulted in approximately 550 confirmed cases and 101 deaths. Health experts estimate the strain’s case fatality rate can reach up to 40%.

In response, global partners including the World Health Organization are evaluating a range of experimental vaccines, antibody therapies, and antiviral drugs. Most of these candidates remain in early development stages and would require emergency or compassionate-use authorization before deployment.

Vaccine candidates

The World Health Organization has identified several promising vaccine candidates targeting BDBV.

One leading candidate is a single-dose rVSV-based vaccine developed by the International AIDS Vaccine Initiative. The vaccine, rVSVΔG/BDBV-GP, uses the same platform as Merck’s approved Ervebo vaccine for the Zaire strain. Preclinical studies in non-human primates have shown survival benefits. The program is advancing toward clinical trials, supported by funding from the Coalition for Epidemic Preparedness Innovations, which has committed initial support to accelerate development.

Another candidate, ChAdOx1 Bundibugyo, is being developed by the University of Oxford in collaboration with the Serum Institute of India. Built on the same ChAdOx1 platform used in the Oxford/AstraZeneca COVID-19 vaccine, the project is being fast-tracked under emergency response mechanisms. Early estimates suggest doses could be ready for clinical evaluation within two to three months, pending additional preclinical work.

Moderna is also collaborating with CEPI to advance an mRNA-based Bundibugyo vaccine into preclinical and early clinical testing, with funding support potentially reaching tens of millions of dollars depending on results.

A separate candidate from privately held Public Health Vaccines is also under development using an rVSV platform similar to existing Ebola vaccines.

Antibody-based therapies

Among therapeutic options, the World Health Organization has prioritized several monoclonal antibody treatments for clinical evaluation.

One leading candidate is MBP134, developed by Mapp Biopharmaceutical. The therapy is a combination of two human monoclonal antibodies designed to target multiple Ebola species. Early-stage trials have shown the treatment is safe and well tolerated, and it has received development support from the U.S. Biomedical Advanced Research and Development Authority (BARDA). The therapy is now being prepared for potential deployment in outbreak settings under clinical trial protocols.

Regeneron Pharmaceuticals is also evaluating its antibody candidate maftivimab, which laboratory studies suggest may have activity against the Bundibugyo strain. The company has also provided doses of its approved Ebola treatment Inmazeb for potential evaluation in the outbreak response.

In addition, researchers are exploring survivor-derived monoclonal antibodies, including BDBV289-N, which showed strong protective effects in animal studies, including high survival rates in infected non-human primates even when treatment was delayed.

Antiviral drugs

The antiviral pipeline includes both experimental and repurposed therapies.

Gilead Sciences is evaluating its oral antiviral obeldesivir as a potential post-exposure treatment. Preclinical studies in primates have shown strong protective effects against multiple Ebola strains, and researchers believe it may also be active against Bundibugyo.

The company’s intravenous antiviral remdesivir has also demonstrated laboratory activity against BDBV in studies conducted by academic researchers, with some evidence suggesting stronger activity against Bundibugyo than against other Ebola strains.

The World Health Organization is also reviewing combination therapies involving monoclonal antibodies and antivirals for potential clinical use.

Diagnostic testing

Limited diagnostic capacity has been identified as a key challenge in controlling the outbreak, prompting efforts to expand testing tools.

Roche has developed a research-use molecular PCR test capable of detecting Bundibugyo ebolavirus and is working with public health partners to expand availability in affected regions.

bioMérieux, through its BioFire Defense unit, offers a multiplex fever panel that can detect multiple Ebola species, including Bundibugyo. Production capacity is being increased to meet potential demand.

Germany-based Altona Diagnostics has also deployed its RealStar Filovirus RT-PCR kit to support outbreak detection in the Democratic Republic of Congo, with expanded production to support ongoing testing needs.

Outlook

While no approved treatments or vaccines currently exist for Bundibugyo ebolavirus, the coordinated global response has rapidly mobilized multiple experimental platforms across vaccines, antibodies, antivirals, and diagnostics.

Health authorities emphasize that most candidates remain in early development stages, but the unusually fast progression of several programs reflects lessons learned from previous Ebola outbreaks and the urgency of containing the current spread in Central Africa. -Reporting by Mariam Sunny in Bengaluru and Jennifer Rigby in Geneva; Editing by Josephine Mason, Rod Nickel, Diti Pujara, Shinjini Ganguli and Shilpi Majumdar/Reuters