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Expert groups convened by the World Health Organization (WHO) have recommended the inclusion of two additional Ebola vaccine candidates in the ongoing Tumaini clinical trial in the Democratic Republic of the Congo (DRC).
The move marks the first time that vaccines specifically developed to protect against Bundibugyo virus, which is responsible for the current Ebola outbreak, will be tested during an active outbreak.
The two candidates are ChAdOx1, developed by the University of Oxford in partnership with the Serum Institute of India, and mRNA-1469, developed by Moderna.
WHO’s independent Technical Advisory Group on Candidate Vaccines Prioritization recommended both candidates for further clinical evaluation this week, following a review of available preclinical and early clinical evidence.
The companies have been notified, and the vaccines will enter the trial once national approvals are secured.
Commenting on the development, WHO Director-General Dr Tedros Adhanom Ghebreyesus said, “The fact that these vaccines are ready to enter clinical trials is a testament to the power of science and partnership.”
He also acknowledged the contributions of scientists, healthcare workers and partners in the DRC and elsewhere, particularly the trial participants, whose involvement would help generate vital evidence that could potentially save lives.
“Vaccines alone will not end this outbreak, but they could become a powerful new tool for bringing it under control,” Tedros added.
Tumani vaccines trial
The Tumaini trial is being led by the Institut National de Recherche Biomédicale (INRB), the DRC’s national public health and biomedical research institute, in collaboration with the University of Antwerp, Belgium. WHO, Epicentre, Médecins Sans Frontières, the Institute of Tropical Medicine of Antwerp, the Africa Centres for Disease Control and Prevention, the DRC Ministry of Health and the Institut National de Santé Publique are also supporting the initiative.
The development of the vaccine candidates has been supported by investments from the Coalition for Epidemic Preparedness Innovations (CEPI).
The Tumaini trial uses a ring-vaccination strategy to evaluate multiple vaccine candidates within a single study. Under this approach, people who have been in contact with confirmed Bundibugyo virus disease cases are enrolled for vaccination.
The strategy builds on the approach used by WHO and its partners during the West Africa Ebola outbreak a decade ago. A landmark trial in Guinea during that outbreak demonstrated the efficacy of Ervebo against Ebola virus, also known as Zaire ebolavirus.
Ervebo is the first vaccine being assessed in the Tumaini trial for its ability to protect against Bundibugyo virus.
Four vaccination rings have already been established, with additional rings being prepared. These include contacts of individuals who have developed the disease or died from Ebola.
Treatment trials underway
Alongside vaccine research, studies are also evaluating potential treatments for Bundibugyo virus disease.
The WHO-sponsored PARTNERS trial, launched in July, is investigating whether the monoclonal antibody MBP134, the antiviral drug remdesivir or a combination of the two can improve survival among patients with confirmed infection.
Maftivimab is also expected to be included in the trial to assess its potential as a treatment. Separately, a post-exposure prophylaxis study involving obeldevisir is underway.
Initial findings from the treatment studies are expected in the coming months, while results from the vaccine trial are anticipated in early 2027.
