DR Congo Ebola outbreak becomes deadliest with over 2,300 deaths

The Coalition for Epidemic Preparedness Innovations (CEPI) has pledged $4.17 million to fund four research initiatives investigating whether existing Ebola vaccines can elicit immune responses against the Bundibugyo virus. These studies aim to analyze stored blood samples from individuals previously vaccinated against Zaire ebolavirus, including recipients of the Ervebo vaccine. This effort seeks to determine if these vaccines could offer some level of protection against different strains of the Ebola virus. The research coincides with an ongoing outbreak of the Bundibugyo virus in the Democratic Republic of the Congo (DRC). The World Health Organisation (WHO) has classified the outbreak as the second-largest in history, with 4,665 confirmed cases and 2,184 fatalities recorded across five provinces and 54 health zones. The organization declared the outbreak a Public Health Emergency of International Concern in May. Currently, there is no licensed vaccine specifically approved for Bundibugyo Ebola virus disease, according to CEPI's Chief Executive Officer, Richard Hatchett. While specific vaccine candidates for Bundibugyo are under development, they are unlikely to be available during the initial stages of the outbreak. However, vaccines for the related Zaire ebolavirus, including Ervebo, are already available. With the recent announcement that Ervebo will be deployed for emergency use against Bundibugyo virus, these CEPI-funded studies will play a crucial role in determining how best to utilize the existing vaccine. The WHO Technical Advisory Group on Candidate Vaccine Prioritisation has recommended that Ervebo be assessed in a phase three clinical trial alongside Bundibugyo-specific vaccine candidates once they become available. Additionally, DRC authorities and the Africa Centres for Disease Control and Prevention have announced plans to deploy Ervebo to priority groups under a protocol-governed expanded-use arrangement. The funding for these studies comes from multiple sources, including the European Commission via a 2026 Horizon Europe grant, the United States Department of State, and CEPI’s existing core funding. The research aims to fill critical knowledge gaps regarding the potential use of existing vaccines against the Bundibugyo virus and support vaccination decisions during the current outbreak and future responses. The four projects will investigate whether vaccination against Zaire ebolavirus can produce antibody responses that recognize the Bundibugyo virus. Researchers will also develop and standardize antibody tests for the Bundibugyo virus and explore the duration of such immune responses. These studies will prioritize tests for the Bundibugyo virus and examine which vaccines may offer cross-protection. Part of the funding will enable the transfer of these laboratory methods to the Institut National de Recherche Biomédicale (INRB) in the DRC, aligning their laboratory capabilities with CEPI’s Centralized Laboratory Network and international antibody reference standards. Initial antibody results are anticipated within two to six months. The University of California, Los Angeles (UCLA) Fielding School of Public Health will receive $2.05 million for its study, focusing on blood samples from more than 1,700 individuals who received Ervebo and another Ebola vaccine. This research will contribute to understanding the breadth and durability of immune responses generated by these vaccines. The DRC has received an initial allocation of 70,000 doses of the Ervebo vaccine to aid in responding to the Bundibugyo outbreak. Of these, 20,000 will be used in a Phase III clinical trial to evaluate the vaccine’s efficacy against the Bundibugyo virus, while the remaining 50,000 doses will be distributed to frontline and healthcare workers following WHO guidelines. The decision to conduct a clinical trial reflects uncertainties about the effectiveness of Ervebo against the Bundibugyo virus. Although Ervebo is licensed for use against the Zaire species of Ebola virus, its effectiveness against the Bundibugyo strain is still unknown. Early laboratory and animal studies suggest it may offer some protection, but further evidence is needed. Participants in the trial, whether as part of the study or outside it, must be fully informed about the potential risks, benefits, and limitations of using Ervebo against the Bundibugyo virus and must provide informed consent. The outbreak has spread beyond the initial epicenter in Ituri Province to 54 health zones across six provinces, marking it as the largest Ebola outbreak ever recorded in the DRC. Factors contributing to the rapid spread include population movements, insecurity, artisanal mining activities, and cross-border travel involving neighboring countries. The situation has intensified pressure on health authorities and researchers to implement available interventions while developing targeted tools for the Bundibugyo virus. In July, the first human clinical trial of an experimental Bundibugyo Ebola vaccine began at the University of Oxford. Known as BD-Ebov, this Phase I trial is evaluating the safety and immunogenicity of the ChAdOx1 BDBV vaccine in healthy adults. Developed by the University of Oxford’s Oxford Vaccine Group and Pandemic Sciences Institute in collaboration with the Serum Institute of India and CEPI, this vaccine is specifically designed to target the Bundibugyo virus. Unlike Ervebo, which is licensed for use against Zaire ebolavirus, ChAdOx1 BDBV is tailored to combat the Bundibugyo strain. The use of Ervebo in the current outbreak serves a dual purpose: protecting high-risk health workers and generating data on whether an existing Ebola vaccine can offer protection against a different species of the virus. The WHO’s technical advisory group on candidate vaccine prioritisation has endorsed this approach, emphasizing the need for both immediate intervention and long-term research into effective vaccines for the Bundibugyo strain. The Ebola outbreak in the DRC has become the deadliest in the country’s history, with over 2,300 fatalities reported since the outbreak was declared in May. As of the latest update, 4,945 confirmed cases have been recorded, with 101 new cases reported in a single day. The virus has spread to six of the country’s 26 provinces, raising concerns about the speed of transmission. The outbreak is attributed to the Bundibugyo species, a rare strain with only two previous known outbreaks. Public health officials have described the outbreak as exceptionally fast-moving, with the United Nations humanitarian chief warning that the epidemic was killing approximately one person every 30 minutes at its peak. While the virus has primarily remained within the DRC, cases have been reported in neighboring Uganda and a few instances in Europe. Efforts are underway to contain the outbreak, with the WHO aiming to bring transmission under control within three months. Health officials caution that controlling transmission does not guarantee the immediate end of the outbreak. Scientists continue to work on developing vaccines against the Bundibugyo strain. Britain’s medicines regulator has approved human trials of a vaccine developed by researchers at the University of Oxford, utilizing technology similar to that used in the Oxford-AstraZeneca COVID-19 vaccine. Ebola is a rare but highly dangerous viral disease characterized by symptoms such as fever, headache, and fatigue, progressing to vomiting and diarrhea in severe cases. Transmission occurs primarily through direct contact with the blood or other bodily fluids of an infected individual. The latest outbreak marks the 17th recorded Ebola outbreak in the DRC since the virus was first identified there 50 years ago. Years of conflict, population movement, and strain on the country’s health system have complicated efforts to control outbreaks. With cases continuing to rise rapidly, health authorities are enhancing surveillance, treatment, and infection-control measures to slow the spread of the disease. Despite these efforts, the challenge of containing the outbreak persists, underscoring the urgent need for effective vaccines and interventions tailored to the Bundibugyo strain.