The World Health Organization (WHO) has recommended adding two new Ebola vaccine candidates to an ongoing clinical trial in the Democratic Republic of the Congo (DRC). The move marks an important step in efforts to develop vaccines against the Bundibugyo virus, which is responsible for the current Ebola outbreak.
The recommendation also marks the first time that vaccines specifically developed to protect against the Bundibugyo virus will undergo evaluation during an active outbreak.
Two New Vaccine Candidates Recommended
The two vaccine candidates are ChAdOx1, developed by the University of Oxford in collaboration with the Serum Institute of India, and Moderna’s mRNA-1469.
WHO’s independent Technical Advisory Group on Candidate Vaccine Prioritization recommended both candidates for further clinical evaluation based on available preclinical and early clinical evidence. The candidates will join the ongoing Tumaini trial once they receive the necessary national approvals.
WHO Director-General Dr Tedros Adhanom Ghebreyesus highlighted the importance of scientific collaboration and clinical research in tackling the outbreak. He noted that the participation of researchers, healthcare workers and trial volunteers would help generate vital evidence to support future outbreak responses.
Tumaini Trial to Evaluate Multiple Vaccines
The National Institute of Biomedical Research (INRB) in the DRC is leading the vaccine trial, with support from the University of Antwerp, WHO, Epicentre, Médecins Sans Frontières, the Institute of Tropical Medicine of Antwerp and the Africa Centres for Disease Control and Prevention.
The Coalition for Epidemic Preparedness Innovations (CEPI) has also supported the rapid development of the vaccine candidates through its investments.
The Tumaini trial uses a ring-vaccination approach to evaluate multiple vaccine candidates within a single study. Under this approach, researchers vaccinate contacts of people with confirmed Bundibugyo virus disease to assess vaccine effectiveness.
The trial builds on an approach used during the West Africa Ebola outbreak a decade ago. At that time, a landmark study in Guinea established the effectiveness of Ervebo against the Zaire ebolavirus.
Ervebo is the first vaccine being evaluated in the Tumaini trial to assess its effectiveness against the Bundibugyo virus. So far, researchers have established four vaccination rings and are preparing several more. These rings include contacts of people who have fallen ill or died from the disease.
Ebola Treatment Research Also Progresses
Alongside vaccine development, researchers are advancing clinical studies to identify potential treatments for Bundibugyo virus disease.
The WHO-sponsored PARTNERS trial, launched in July, is evaluating whether the monoclonal antibody MBP134, the antiviral drug remdesivir or a combination of both can improve survival among patients with confirmed infections.
Furthermore, researchers plan to add maftivimab to the trial to assess its potential as a treatment. A separate post-exposure prophylaxis study involving obeldevisir is also underway.
WHO Supports Ebola Research and Clinical Studies
WHO is supporting research activities through its R&D Blueprint and Health Emergencies Programme. Its efforts include developing research protocols, providing technical guidance, coordinating research partners and supporting the integration of ethical and scientifically rigorous studies into the outbreak response.
Initial findings from the treatment trials are expected in the coming months, while results from the vaccine trial are anticipated in early 2027. As reported by the World Health Organization (WHO), the ongoing research aims to strengthen the scientific evidence available for preventing and treating Bundibugyo virus disease and improving responses to future Ebola outbreaks.