In a significant development for global health security, Gavi, the Vaccine Alliance, has enthusiastically welcomed a pivotal recommendation from the World Health Organization (WHO). This recommendation suggests that Ervebo (rVSV-ZEBOV), an approved vaccine widely used against the Zaire strain of Ebola, should be prioritized for large-scale (Phase 3) clinical trials to combat Bundibugyo virus disease (BVD). This strategic decision comes as the Democratic Republic of Congo (DRC) grapples with a concerning outbreak, highlighting the urgent need for effective interventions. The move aims to leverage a proven vaccine while parallel efforts continue to develop a specific shot for Bundibugyo. ## A Strategic Move Against Bundibugyo The WHO Technical Advisory Group on candidate vaccine prioritization (TAG-CVP) for Bundibugyo virus disease outbreak response made the crucial recommendation. Their decision to consider Ervebo for direct entry into Phase 3 evaluations for Bundibugyo stems from the substantial amount of safety and immune response data already available for the vaccine. Ervebo has a strong track record, having been instrumental in controlling several outbreaks of the Zaire Ebola virus over the last decade. This extensive prior knowledge makes it a promising candidate for rapid assessment against a closely related, yet distinct, threat like Bundibugyo. For the general public, understanding a Phase 3 trial is important. It represents a critical stage in vaccine development where thousands of people participate to confirm the vaccine's effectiveness and safety in a real-world setting, significantly larger than earlier trial phases. This step is essential before a vaccine can be officially approved and widely distributed. By recommending direct Phase 3 entry, experts believe Ervebo can quickly provide critical insights into its potential to protect against Bundibugyo, potentially speeding up life-saving interventions. ## Understanding Bundibugyo Virus Disease Bundibugyo virus disease (BVD) is one of several types of Ebola virus disease, caused by the Bundibugyo virus, a member of the *Filoviridae* family, just like the Zaire Ebola virus. While sharing many similarities with the more commonly known Zaire Ebola, Bundibugyo presents its own unique challenges and clinical characteristics. Symptoms typically include fever, severe headache, muscle pain, weakness, fatigue, and can progress to vomiting, diarrhea, rashes, impaired kidney and liver function, and in some cases, both internal and external bleeding. The disease has a high fatality rate, underscoring the urgency for effective prevention and treatment strategies. Outbreaks of Bundibugyo, much like Zaire Ebola, are particularly devastating in regions with limited healthcare infrastructure, such as parts of the DRC. The virus spreads through direct contact with blood, secretions, organs, or other bodily fluids of infected people, and from contaminated surfaces and materials. Controlling such outbreaks requires rapid identification, isolation, contact tracing, and, crucially, effective vaccination to break chains of transmission. The current outbreak in the DRC, described by Gavi as already the largest Ebola outbreak in the country's history and potentially the largest ever, highlights the immense pressure on communities and frontline health workers. ## Leveraging Global Vaccine Stockpiles A critical element in this rapid response strategy is the global Ebola vaccine stockpile. Established and funded by Gavi and managed by the Interagency Coordination Group on Vaccine Provision (ICG)—a partnership involving WHO, UNICEF, the International Federation of Red Cross and Red Crescent Societies (IFRC), and Médecins Sans Frontières (MSF)—this stockpile holds ready-to-deploy doses of Ervebo. The recommendation ensures that doses from this vital resource will be made available to support the planned Phase 3 trials. The genesis of this stockpile goes back to the devastating 2014-2016 West Africa Ebola outbreak, where the absence of approved vaccines severely hampered response efforts. Gavi stepped in, committing an Advance Purchase Commitment that secured 300,000 investigational doses of the then-candidate Ervebo vaccine. This commitment not only facilitated immediate response but also helped accelerate the path to WHO prequalification by guaranteeing a permanent market for the vaccine. Officially launched in 2021, the stockpile is meticulously maintained at 500,000 Ervebo doses, with some strategically pre-positioned in the DRC due to the country's higher prevalence of outbreaks. This strategic readiness ensures that any country facing an outbreak can quickly access these life-saving vaccines, with lower-income countries eligible for free doses and accompanying financial support for vaccination activities. ## Accelerating Bundibugyo-Specific Solutions It is important to emphasize that the trial of Ervebo for Bundibugyo is not a standalone solution but a complementary effort to ongoing research. While Ervebo offers a pragmatic, immediate option due to its existing data, the development of a vaccine specifically designed for Bundibugyo remains a high priority. Gavi is actively supporting this long-term goal through a substantial US$40 million investment from its First Response Fund. This funding aims to accelerate the development and scale-up of promising Bundibugyo-specific vaccine candidates for investigational use during outbreaks and, ultimately, for full WHO pre-qualification. The pursuit of a Bundibugyo-specific vaccine ensures that, in the future, the world will have the most targeted and potentially most effective tool against this particular strain. This dual approach—using a readily available, broadly effective vaccine now while investing in specialized solutions for tomorrow—demonstrates a comprehensive strategy to combat emerging infectious diseases. It highlights a commitment to both immediate crisis management and long-term preparedness. ## Gavi's Broader Commitment to Ebola Prevention Gavi's involvement extends beyond emergency stockpiles and trial support. In 2023, Gavi launched a comprehensive preventive Ebola vaccination program for countries at the highest risk, aligning with updated WHO guidance. This initiative makes the best use of available stockpile doses to protect vulnerable populations before outbreaks occur. As part of this program, approximately 55,000 frontline health workers in high-risk areas like Ituri and North Kivu in the DRC have already received Ervebo through preventive vaccination campaigns. This proactive approach is crucial for safeguarding healthcare systems and preventing the spread of the virus within communities. Dr. Sania Nishtar, CEO of Gavi, the Vaccine Alliance, underscored the severity of the situation, noting, “This is already the largest Ebola outbreak in DRC’s history, and could well become the largest outbreak ever.” She expressed encouragement that the approved Ervebo vaccine, readily available through the Gavi-funded global stockpile, could significantly help reduce severe illness and deaths. Gavi remains steadfast in its commitment to supporting these trials alongside its ongoing work to accelerate access to promising Bundibugyo-specific candidates. ## Why Rapid Action Matters in Outbreaks The ability to act swiftly and decisively is paramount when dealing with highly contagious and deadly diseases like Ebola. The rapid deployment of vaccines, even if initially for trials, can dramatically alter the course of an outbreak. By reducing severe illness and deaths, such interventions alleviate the burden on already strained healthcare systems, protect essential frontline workers, and restore a sense of safety within affected communities. Each day saved in vaccine development and deployment translates into fewer infections and more lives preserved. This proactive and adaptable strategy, combining existing tools with focused research, is critical for building resilient health systems and safeguarding global public health against future threats.