WHO recommends two new Bundibugyo Ebola vaccine candidates for DRC trial

DRC—The World Health Organization (WHO) has recommended two additional Ebola vaccine candidates for clinical evaluation in the Democratic Republic of the Congo (DRC) to expand protection against the ongoing Bundibugyo virus outbreak.

The candidates are ChAdOx1, developed by the University of Oxford in partnership with the Serum Institute of India, and Moderna’s mRNA-1469.

Both have been recommended by WHO’s independent Technical Advisory Group on Candidate Vaccine Prioritization following a review of available preclinical and early clinical evidence.

The developers were notified on Monday, and the candidates will enter the ongoing Tumaini clinical trial once national approvals are secured.

This marks the first time vaccines specifically developed against Bundibugyo virus will undergo evaluation during an outbreak caused by the virus.

Commenting on the development, WHO Director-General Dr Tedros Adhanom Ghebreyesus said the readiness of the candidates for clinical evaluation demonstrates the value of scientific research and international collaboration.

He acknowledged the contributions of researchers, healthcare workers and partners in the DRC and internationally, particularly the volunteers participating in the trial.

Their involvement, he noted, will generate evidence that could support efforts to save lives.

He also stressed that vaccination would complement, rather than replace, other outbreak control measures.

Multiple vaccine candidates enter clinical evaluation

The Institut National de Recherche Biomédicale (INRB), the DRC’s national biomedical research institute, is leading the vaccine trial.

Its partners include 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.

Funding from the Coalition for Epidemic Preparedness Innovations (CEPI) has supported the accelerated development of the vaccine candidates.

The Tumaini trial uses a ring-vaccination approach, targeting people who have had contact with confirmed Bundibugyo virus disease cases.

This strategy builds on the approach used during the 2014–2016 West Africa Ebola outbreak, when a landmark clinical trial in Guinea established Ervebo’s efficacy against Zaire ebolavirus.

Ervebo is already being evaluated in the Tumaini trial to determine its effectiveness against Bundibugyo virus, although it was originally developed to protect against Zaire ebolavirus.

Four vaccination rings have been established, with additional groups being prepared.

These include contacts of people who have developed the disease or died from the infection.

Treatment research expands alongside vaccine development

WHO is also supporting investigations into potential treatments through the PARTNERS trial, launched in July.

The study is assessing whether the monoclonal antibody MBP134, the antiviral drug remdesivir or a combination of both can improve survival among patients with confirmed Bundibugyo virus disease.

Maftivimab is expected to join the trial for evaluation as another potential treatment, while a separate study is investigating obeldevisir for post-exposure prophylaxis.

Through its Research and Development Blueprint and Health Emergencies Programme, WHO is coordinating research activities, developing protocols, advising partners and providing operational support to ensure clinical studies meet scientific and ethical standards during the outbreak.

Initial findings from the treatment studies are expected in the coming months, while results from the vaccine trial are anticipated in early 2027.

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