The announcement by the UN World Health Organization (WHO) follows the recommendation of its independent Technical Advisory Group on Candidate Vaccines Prioritization.

This will mark the first time that vaccines specifically designed for Bundibugyo virus will be evaluated during an outbreak of the disease.

“The fact that these vaccines are ready to enter clinical trials is a testament to the power of science and partnership,” said WHO Director-General Tedros Adhanom Ghebreyesus.

He stressed that while vaccines alone will not end the outbreak, “they could become a powerful new tool for bringing it under control”.

‘Hope’ as cases mount

The two vaccine candidates are ChAdOx1, developed by the University of Oxford with the Serum Institute of India, and mRNA-1469, developed by the American pharmaceutical and biotech company Moderna.

WHO convened the expert group which this week recommended them for further clinical evaluation, based on available evidence.

The DRC has been battling a deadly outbreak of Ebola disease caused by the rare Bundibugyo virus species for nearly six months and it has become the largest in the country’s history. As of 1 November, there were more than 10,500 confirmed cases and 5,126 deaths.

WHO is supporting the Tumaini multi-vaccine trial, named after the Swahili word for “hope”. It was launched on 23 October in the eastern city of Bunia, capital of Ituri province, which remains the epicentre of the outbreak.

The Ervebo vaccine, used to treat the Zaire species of the Ebola virus, is already being tested to determine if it is effective against Bundibugyo species. The two new vaccine candidates will enter the trial following national approvals.

Tumaini is designed to test multiple vaccine candidates within a single trial, using a ring-vaccination approach that focuses on contacts of people with confirmed Ebola Bundibugyo.

WHO and partners pioneered the strategy during the West Africa Ebola outbreak a decade ago, where a trial in Guinea established the efficacy of the Ervebo vaccine.

Four vaccination rings have been set up and several more are being prepared, while research into other potential treatments is also moving forward.