WHO Recommends Candidate Vaccines and Therapeutics for Bundibugyo Virus Outbreak

As the ongoing outbreak of Bundibugyo virus disease (BVD)—a rare but deadly form of Ebola—continues to spread across the Democratic Republic of the Congo (DRC) and into neighboring Uganda, the World Health Organization (WHO) has convened expert panels to assess potential treatments and vaccines. With no licensed therapies or vaccines currently approved for BVD, WHO’s advisory groups have prioritized several experimental candidates for clinical trials, emphasizing the urgent need for rigorous evaluation to curb transmission and save lives.

The WHO’s R&D Blueprint technical advisory groups, alongside the Strategic Advisory Group of Experts on Immunization (SAGE), reviewed promising candidates for both treatment and prevention. Their recommendations focus on accelerating research while adhering to strict ethical and safety standards, particularly in high-risk regions where healthcare infrastructure is strained.

Key Recommendations: Prioritizing Science Over Speculation

Given the absence of approved treatments for BVD, WHO’s experts identified three candidate therapeutics for immediate evaluation in clinical trials among confirmed cases:

• Monoclonal antibodies: MBP134 and Maftivimab®, which target the virus to neutralize its effects.
• Antiviral drug: Remdesivir, previously studied for Ebola and other viral infections, with potential for combination therapy when paired with monoclonal antibodies.

For prevention, experts highlighted two approaches:

• Post-exposure prophylaxis: The oral antiviral obeldesivir was deemed a priority for contacts of confirmed or probable BVD cases. However, its effectiveness hinges on robust contact tracing—a challenge in conflict-affected regions of the DRC.
• Vaccine candidates:
  • The rVSV Bundibugyo vaccine (developed by the International AIDS Vaccine Initiative, IAVI) is the most advanced single-dose option but requires 7–9 months before clinical trial readiness.
  • The ChAdOx1 Bundibugyo vaccine (Oxford University/Serum Institute of India) could be available within 2–3 months for efficacy testing, though additional animal data are needed to confirm its safety and effectiveness. Experts suggest a single-dose regimen for exposed contacts and a two-dose strategy for high-risk groups like healthcare workers.
• Ervebo (the only licensed Ebola vaccine) is not approved for BVD and shows limited evidence of cross-protection against the Bundibugyo strain. WHO advises against its use outside clinical trials to avoid obscuring data on its potential effectiveness.

Ethical Trials and Urgent Public Health Measures

WHO is collaborating with the governments of the DRC and Uganda, the Africa Centres for Disease Control and Prevention (Africa CDC), and global partners to design and implement clinical trials under strict ethical guidelines. The priority remains stopping transmission using proven tools: surveillance, rapid testing, contact tracing, isolation, infection control, community engagement, and safe burials.

Dr. Tedros Adhanom Ghebreyesus, WHO Director-General, emphasized the need for accelerated access to supplies, community trust, and coordinated investment in research. “All research must prioritize the well-being of participants and communities,” he stated, underscoring that ethical oversight and transparency are non-negotiable.

Why This Matters: A Race Against Time

The Bundibugyo virus, one of six Ebola virus species, has historically caused sporadic outbreaks with high fatality rates. Unlike the more studied Zaire ebolavirus (responsible for the 2014–2016 West Africa outbreak), BVD lacks approved countermeasures, leaving responders reliant on generic Ebola response strategies. The current outbreak—first detected in the DRC in February 2024 and spreading to Uganda—highlights the critical gap in preparedness for lesser-known but equally lethal pathogens.

WHO’s R&D Blueprint, activated during this crisis, is designed to fast-track the development of medical countermeasures during epidemics. Meanwhile, SAGE’s role in vaccine advisory ensures that any new tools are evaluated for safety, efficacy, and equitable distribution. The challenge lies in balancing speed with scientific rigor, particularly in regions where healthcare systems are fragile and misinformation can undermine public trust.

What Comes Next: Uncertainty and Hope

While clinical trials for the prioritized candidates are underway, experts caution that results may take months to materialize. In the interim, WHO and partners are scaling up existing measures to contain the outbreak. The focus remains on:

• Strengthening surveillance to detect cases early and trace contacts.
• Enhancing laboratory capacity for rapid diagnosis.
• Protecting frontline workers with personal protective equipment and training.
• Engaging communities to build trust and encourage reporting.

For the millions at risk, the race is not just against the virus but against time. As WHO’s 2026 World Health Day campaign “Together for health. Stand with science” underscores, evidence-based solutions—however incremental—are the only path forward. In the case of BVD, those solutions are still being tested, but the stakes could not be higher.

For updates on this outbreak and WHO’s response, visit the WHO Ebola page.