WHO Prioritizes Vaccines and Treatments as Ebola Bundibugyo Outbreak Raises Concerns

The World Health Organization (WHO) has intensified efforts to combat the ongoing outbreak of Ebola disease caused by the Bundibugyo virus in the Democratic Republic of the Congo (DRC), with related cases also reported in neighboring Uganda. As health authorities work to contain the spread of the disease, international experts have identified several promising vaccine and treatment candidates that could play a crucial role in future outbreak responses.

However, WHO has emphasized that none of the currently available candidates has been approved specifically for Bundibugyo virus disease (BVD), consequently, all proposed vaccines and therapeutics should only be used within carefully designed clinical trials to ensure their safety, effectiveness and ethical evaluation.

The recommendations emerged following consultations involving several WHO expert advisory groups, including scientific specialists on Ebola vaccines, therapeutics and immunization strategies. The discussions focused on identifying the most promising interventions for preventing infections and treating patients during the current outbreak.

Bundibugyo Virus: A Less Common but Serious Ebola Strain

The Bundibugyo virus is one of several viruses belonging to the Ebola family and is responsible for causing Bundibugyo virus disease, a severe and often fatal illness characterized by fever, weakness, vomiting, diarrhea and, in some cases, internal and external bleeding.

Although less common than the Zaire Ebola virus strain, which has caused several major outbreaks in Africa, Bundibugyo virus remains a significant public health threat due to its potential to spread rapidly and cause severe illness.

The current outbreak has renewed concerns among health authorities because there are currently no licensed vaccines or treatments specifically approved for Bundibugyo virus disease. This creates an urgent need for research into effective medical countermeasures while continuing to rely on proven outbreak-control strategies.

Experts Identify Promising Treatment Candidates

One of the key outcomes of the WHO consultations was the identification of several therapeutic candidates that could potentially improve survival rates among infected patients.

Independent experts recommended prioritizing three treatments for evaluation through clinical trials involving confirmed Bundibugyo virus disease cases:

• MBP134, a monoclonal antibody therapy;

• Maftivimab®, another monoclonal antibody treatment;

• Remdesivir, an antiviral medication that has been studied for multiple viral diseases.

Researchers also recommended evaluating combination therapy approaches that pair a monoclonal antibody treatment with remdesivir. Such combinations may enhance treatment effectiveness by attacking the virus through multiple mechanisms.

Clinical trials will be necessary to determine whether these therapies can safely reduce disease severity, improve recovery rates and decrease mortality among infected patients.

New Strategies for Post-Exposure Protection

Experts also explored preventive measures for individuals who may have been exposed to the virus through contact with confirmed or suspected cases.

A promising candidate identified for post-exposure prophylaxis is obeldesivir, an oral antiviral medication that could potentially prevent the development of disease after exposure.

The proposed strategy would involve administering obeldesivir tablets to people who have recently come into contact with infected individuals and then monitoring whether the treatment reduces infection rates.

However, specialists noted that the success of such an approach depends heavily on effective contact tracing systems. Identifying and monitoring all potential contacts remains a significant challenge, particularly in remote or resource-constrained areas where health systems may face logistical difficulties.

Despite these challenges, post-exposure prevention strategies could become an important tool in future Ebola outbreak responses if proven effective.

Vaccine Development Accelerates

In addition to treatment options, WHO experts reviewed several vaccine candidates currently under development for Bundibugyo virus disease.

The most promising candidate identified was the single-dose rVSV Bundibugyo vaccine, being developed by the International AIDS Vaccine Initiative (IAVI).

Experts believe this vaccine has strong potential for protecting individuals against Bundibugyo virus infection. However, additional development work is required before it can be tested in large-scale clinical trials.

Current estimates suggest the vaccine could be ready for efficacy studies within approximately seven to nine months.

If successful, the vaccine could become an important tool for protecting communities during future outbreaks.

Another Vaccine Candidate Could Be Available Sooner

A second vaccine candidate attracting attention is ChAdOx1 Bundibugyo, developed through collaboration between Oxford University and the Serum Institute of India.

Researchers believe this vaccine may be available for evaluation within two to three months, potentially making it one of the first candidates ready for clinical assessment during the current outbreak.

However, experts stressed that additional animal studies are still required before broader prioritization decisions can be made.

The vaccine offers flexibility in how it could be deployed. A single-dose strategy may be appropriate for contacts of confirmed Ebola cases, while a two-dose schedule could potentially provide protection for high-risk populations such as healthcare workers, laboratory staff and frontline emergency responders.

Questions Remain About Existing Ebola Vaccines

WHO experts also examined whether Ervebo, the only currently licensed Ebola vaccine, could provide protection against Bundibugyo virus disease.

Ervebo has proven highly effective during outbreaks caused by the Zaire Ebola virus species and has been widely used in several African countries.

However, Bundibugyo virus belongs to a different species within the Ebola virus family. Current evidence regarding cross-protection between Ebola species remains limited and inconclusive.

As a result, WHO does not recommend using Ervebo for Bundibugyo virus outbreaks outside carefully controlled research settings. Any use of the vaccine against Bundibugyo virus should occur only through clinical studies designed to generate reliable scientific evidence.

International Collaboration to Advance Research

To accelerate progress, WHO is working closely with the governments of the Democratic Republic of the Congo and Uganda, as well as a range of international partners.

These include the Africa Centres for Disease Control and Prevention (Africa CDC), the French National Agency for Research on AIDS and Viral Hepatitis (ANRS Emerging Infectious Diseases), research institutions and public health organizations.

Together, these partners are developing clinical trial protocols that will enable scientists to assess the safety and effectiveness of prioritized vaccines and therapeutics under real outbreak conditions.

The collaborative approach aims to ensure that research findings are scientifically robust while also supporting public health efforts to contain the outbreak.

Ethical Standards Remain a Top Priority

WHO has emphasized that all research activities must adhere to the highest ethical and scientific standards.

National health authorities will lead the implementation of clinical trials, while affected communities will be actively consulted throughout the research process. Community engagement is considered essential for building trust, encouraging participation and ensuring that studies are conducted respectfully and transparently.

Public health experts stress that ethical considerations are particularly important during emergency outbreaks, where urgent needs must be balanced against scientific rigor and participant safety.

Traditional Ebola Control Measures Remain Essential

While research into vaccines and therapeutics continues, WHO has stressed that the most effective tools currently available remain the proven public health measures used in previous Ebola outbreaks.

These include:

• Disease surveillance and early detection;

• Rapid testing and laboratory diagnosis;

• Contact tracing and monitoring;

• Isolation and treatment of infected individuals;

• Infection prevention and control measures;

• Community engagement and awareness campaigns;

• Safe and dignified burial practices.

These interventions have successfully helped contain numerous Ebola outbreaks over the past several decades and remain the foundation of current response efforts.

Call for Greater Investment and Global Support

WHO is also calling for increased international support to strengthen outbreak response activities and accelerate the development of effective countermeasures against Bundibugyo virus disease.

The organization has urged governments, donors, research institutions and private-sector partners to invest in research, healthcare infrastructure, medical supplies and community protection initiatives.

Enhanced coordination and sustained funding will be essential to advancing clinical trials, improving preparedness and protecting vulnerable populations from future outbreaks.

A Critical Moment for Ebola Research

The current outbreak presents both a public health challenge and an opportunity to expand scientific understanding of Bundibugyo virus disease.

By evaluating promising vaccines and treatments through carefully designed clinical trials, researchers hope to generate the evidence needed to improve future outbreak responses and save lives.

At the same time, health authorities continue to focus on immediate containment efforts, recognizing that strong surveillance systems, rapid response mechanisms and community trust remain the most effective defenses against Ebola transmission.

As international partners work together to confront the outbreak, the lessons learned could help strengthen preparedness not only for Bundibugyo virus disease but also for future emerging infectious disease threats across the region and beyond.