WHO Approves Trials for Two New Bundibugyo Ebola Vaccines

The World Health Organization (WHO) has approved clinical trials for two new Ebola vaccines, both designed specifically for the Bundibugyo strain of the virus, Al Jazeera reported on 4 November. The two candidates are ChAdOx1, developed by the University of Oxford with the Serum Institute of India, and mRNA-1469 from Moderna. A clinical trial is a study in people, and both candidates are expected to join an existing WHO-backed trial in the Democratic Republic of the Congo (DRC).

Ebola is a viral disease, and the Bundibugyo strain is one of several known forms of it. There is currently no approved vaccine for Bundibugyo, and there are no approved treatments for it either. The vaccine already in use against Ebola, Ervebo, was approved for the Zaire strain and is not designed for Bundibugyo. A trial that began in October nonetheless uses Ervebo, and it is the first vaccine in that trial being assessed for its effect against Bundibugyo.

That trial, called TUMAINI, is a pivotal Phase 2/3 study, a late-stage stage of testing. It was launched on 23 October, and the first participant was vaccinated that day in Bunia, in eastern DRC. The DRC's National Institute for Biomedical Research is leading it, with backing from WHO and other partners.

Separately, Oxford began the first human trial of a Bundibugyo Ebola vaccine in July, called BD-Ebov. It will test the safety and immune response to the ChAdOx1 BDBV vaccine in 50 healthy adults. In May, experts convened by WHO judged the single-dose rVSV Bundibugyo vaccine to be the most promising candidate at that stage. In August, WHO and the African Centres for Disease Control and Prevention (Africa CDC) welcomed an allocation of Ebola vaccines to the DRC that includes 20,000 doses for a Phase 3 trial on the Bundibugyo virus.

The outbreak is large. Africa CDC said 10,444 cases of Bundibugyo virus have been confirmed. Since May, the virus has killed more than 5,300 people, most of them in the DRC, and it has a fatality rate of 50 percent. Kenya has reported nine cases, including two deaths, and WHO has confirmed one case in Nigeria.

A British healthcare worker infected with Ebola is being evacuated from the DRC to the United Kingdom for specialist treatment. Earlier, the United States had provided Ebola treatment for the outbreak in Congo, according to Reuters.

Results from the new Bundibugyo vaccine trial are expected in early 2027.