Trials for three potential vaccines targeting the Bundibugyo strain of Ebola in the Democratic Republic of the Congo are scheduled to begin by October or November, according to announcements by the World Health Organization. The announcement comes as the official death toll from the country’s deadliest-ever Ebola outbreak surpasses 3,000 people, with more than 6,000 total infections recorded since the 17th outbreak was officially declared on May 15.
Efficacy Trials and Vaccine Candidates
According to World Health Organization Chief Tedros Adhanom Ghebreyesus, safety trials for two new vaccines against the Bundibugyo virus are currently underway in the United Kingdom and Canada. One of these candidate vaccines is being developed by US-based Moderna utilizing mRNA technology, while the second is being developed by the University of Oxford.
The World Health Organization plans to evaluate multiple vaccine candidates within a single trial framework in the Democratic Republic of the Congo. WHO vaccines chief Kate O’Brien noted that Ervebo, a vaccine manufactured by Merck that is licensed for use against the Zaire strain of Ebola, will likely be the first vaccine introduced into the trial.
Cross-Protection Research and Regional Challenges
Researchers are studying Ervebo to determine whether it offers cross-protection against the Bundibugyo species. While early data derived from animal testing indicates that Ervebo could provide some degree of human protection against the alternate strain, Tedros emphasized that clinical trials remain necessary because definitive efficacy against Bundibugyo is not yet established.
In official recommendations issued on August 31, 2026, the World Health Organization advised that Ervebo should be restricted to clinical trial use during Bundibugyo virus disease outbreaks. O’Brien stated that frontline healthcare workers should also receive Ervebo strictly as part of research into its effectiveness against the strain.
Logistical and medical responses have faced severe hurdles. Although the World Health Organization estimates the virus began circulating undetected as early as late January, responders have scrambled to contain transmission in the restive eastern region of the country, which is heavily impacted by armed groups. A key obstacle has been the lack of approved vaccines or treatments specifically targeting the Bundibugyo Ebola species.
To support frontline deployment, a shipment of 16,250 doses of Ervebo arrived in the Democratic Republic of the Congo in July. Vaccinations for frontline medical personnel commenced shortly afterward in Kisangani, the capital of the northeastern Tshopo province, under targeted research protocols.