When Bundibugyo virus disease emerged in the Democratic Republic of the Congo and crossed borders into Uganda, it brought with it a critical question: what treatments and vaccines could stop its spread? The answer, until now, has been almost nothing. There are currently no licensed therapeutics or vaccines specifically approved for prevention and treatment of Bundibugyo virus disease (BVD)—but that may be changing.
In response to the ongoing outbreak, the World Health Organization convened its expert and advisory groups to assess candidate vaccines and therapeutics for both prevention and treatment of this rare form of Ebola disease. The stakes are high. Unlike the more commonly known Zaire and Sudan strains that have dominated previous outbreaks, Bundibugyo virus has largely eluded medical countermeasures. The WHO's strategic advisory groups, including the Strategic Advisory Group of Experts on Immunization (SAGE) and its Ebola vaccine working group, methodically reviewed every promising option to generate the evidence needed for safe and effective interventions.
For treatment of confirmed cases, the independent experts recommended prioritizing three candidate therapeutics for evaluation in clinical trials. Two are monoclonal antibodies—MBP134 and Maftivimab—that work by helping the body's immune system recognize and fight the virus. The third is remdesivir, an antiviral drug that interferes with the virus's ability to replicate. Experts also recommended evaluating combination therapy using a monoclonal antibody alongside remdesivir, recognizing that layered approaches often prove more effective than single interventions.
For prevention, the focus shifts to contacts of confirmed and probable cases. The oral antiviral obeldesivir emerged as a priority candidate for post-exposure prophylaxis—essentially giving tablets to people exposed to the virus to prevent them from developing disease. However, experts acknowledged a crucial operational reality: this approach depends entirely on effective contact tracing, which remains operationally challenging in some of the affected areas of the Democratic Republic of the Congo.
The vaccine landscape offers more immediate hope. The single-dose rVSV Bundibugyo vaccine, being developed by the International AIDS Vaccine Initiative (IAVI), represents the most promising candidate. While development will likely require 7–9 months before clinical trial assessment begins, it signals a dedicated pipeline. A second candidate, ChAdOx1 Bundibugyo, developed by Oxford University and the Serum Institute of India, could potentially be ready within 2–3 months for efficacy testing, though additional animal data are still needed to confirm its prioritization. For high-risk groups like healthcare workers and frontline responders not yet exposed to the virus, a two-dose strategy might be considered.
WHO also examined Ervebo, the only currently licensed Ebola vaccine. While approved for outbreaks caused by the most common African Ebola virus, it is not licensed for BVD, and evidence on whether it provides cross-protection to Bundibugyo remains limited and inconclusive. The organization recommends against using Ervebo outside carefully designed research settings until its performance against BVD can be assessed.
The WHO, alongside the governments of the Democratic Republic of the Congo and Uganda, the Africa CDC, and the French National Agency for Research on AIDS and Viral Hepatitis, are now working together to develop protocols for rigorous clinical trials. All research will adhere to the highest ethical standards, ensuring that the urgency to develop countermeasures never compromises the safety or dignity of those participating in trials. It marks a pivotal moment: the moment when expert consensus can begin turning possibility into reality.