WHO launches Ebola vaccine trial in eastern DRC

The World Health Organization has announced the beginning of the first clinical trial of an Ebola vaccine during the current outbreak in the Democratic Republic of Congo.

Participants in Bunia, the capital of Ituri province, have received the Ervebo vaccine as part of the Tumaini trial, according to WHO Director-General Tedros Adhanom Ghebreyesus.

The study will examine whether Ervebo, which is approved for use against the more common Zaire strain of Ebola, can provide cross-protection against the Bundibugyo species responsible for the current epidemic.

Trial to use ring vaccination

Tumaini will use a ring vaccination strategy, focusing on contacts considered to be at high risk of infection. The framework is designed to assess the safety, efficacy and immunogenicity of multiple vaccines.

The trial will also incorporate two vaccine candidates specifically developed for Bundibugyo Ebola. One is a ChAdOx1 adenoviral vector vaccine being developed by the University of Oxford, while the other is an mRNA vaccine under development by Moderna.

The Coalition for Epidemic Preparedness Innovations said both candidates had received its funding and were expected to join the trial shortly. The candidates are currently progressing through earlier-stage, smaller-scale clinical trials.

Pregnant women and children aged 12 years and older will be included in the study.

Evidence sought during outbreak

Chikwe Ihekweazu, the WHO’s emergencies director, said the trial was established to produce rigorous evidence on whether the vaccines could protect people at risk.

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

The outbreak began in May and has been described as the Democratic Republic of Congo’s worst-ever Ebola outbreak. It is also reported to have the widest geographic spread of any Ebola outbreak on the African continent to date, with cases recorded in four countries across eastern, central and western Africa.

According to the source report, more than 9,700 cases and over 4,600 deaths have been reported in the DRC outbreak. The country has declared it its 17th Ebola outbreak.

The WHO’s public health emergency of international concern remains in place and is described as the organisation’s second-highest alert level. The effectiveness and safety of the vaccines involved in the Tumaini trial have yet to be determined.