DR Congo starts Ebola vaccine trial in 9,700-case outbreak

WHO Director-General Tedros Adhanom Ghebreyesus said in an X post Friday, Oct. 23, that the Democratic Republic of Congo began the first Ebola vaccine clinical trial in its current outbreak.

The trial gives health authorities a vaccine test in an outbreak now reported in four countries, compared with its start in the DRC, and involving more than 9,700 cases and more than 4,600 deaths.

The trial, called Tumaini, is designed as one framework for testing multiple shots for safety, protective effect and immune response. It uses ring vaccination, meaning contacts considered at high risk of infection are immunised.

“This trial will help us understand whether any of the vaccine candidates designed for Bundibugyo virus work,” Tedros said on X. “WHO is supporting this DRC-led effort to find answers and save lives,” he added.

The first participants received Ervebo in Bunia, the capital of northeastern Ituri province, which WHO identified as the centre of the outbreak. Ervebo is approved for the more common Zaire Ebola strain, and the trial will test whether it also gives protection against Bundibugyo, the species linked to the epidemic.

The Coalition for Epidemic Preparedness Innovations said the trial is expected to add two Bundibugyo-specific vaccine candidates. One is a ChAdOx1 adenoviral vector vaccine from the University of Oxford, a type that uses a modified virus to deliver instructions to human cells. The other is an mRNA vaccine from Moderna, a platform that uses genetic instructions to prompt cells to make a target protein.

CEPI said both candidates have its funding and are expected to join the trial “shortly”. Children aged 12 and above and pregnant women will be included, generating data for groups often left out of clinical research.

WHO emergencies director Chikwe Ihekweazu said the study was established to produce the evidence needed to judge whether the vaccines can protect people exposed to the virus. WHO has triggered a public health emergency of international concern, its second-highest alert level, in response to the outbreak.

The regional context has sharpened the urgency. Atlas360 reported on Oct. 24 that Kenya recorded a second Ebola death in its first outbreak, with seven patients in isolation and officials saying cases were confined to one cluster.

Atlas360 reported on Oct. 23 that an Ebola case in Nigeria with an unknown source raised containment concerns and exposed gaps in cross-border health surveillance data.

What remains unknown is whether Ervebo can protect against Bundibugyo Ebola, or whether the newer candidates will show sufficient safety and protection in a larger human trial. The current outbreak has been reported across eastern, central and western Africa, giving it the widest geographic spread of any Ebola outbreak on the continent to date.

Source: news report, Al Jazeera – Africa/AFP, Oct. 24, 2026.