WHO recommends testing existing Ebola vaccine against Bundibugyo strain in DRC

Moderna ↘ 0.03% has launched the first human clinical trial of an mRNA vaccine targeting Bundibugyo ebolavirus, the strain driving a deadly outbreak in the Democratic Republic of the Congo that has now killed more than 2,100 people and for which no approved vaccine exists.

The company announced on August 4 that the first participants had been vaccinated with mRNA-1469 at three sites in Canada after Health Canada authorized the study. The phase 1 trial aims to enroll approximately 80 healthy adults and will assess safety, tolerability, and whether the vaccine generates an immune response.qz+3

A Race Against a Growing Outbreak

The trial comes as the DRC outbreak continues to accelerate. As of August 11, the CDC reported 4,566 confirmed cases and 2,128 deaths in the DRC, with 20 confirmed cases and two deaths in Uganda. The European Centre for Disease Prevention and Control reported 117 new confirmed cases in a single day. WHO Director-General Tedros Adhanom Ghebreyesus has said the outbreak is on track to become the world's largest, with 75 to 100 new cases being reported daily.miragenews+2

The outbreak, declared a public health emergency of international concern in May 2026, is the second-largest Ebola epidemic on record and the largest ever in the DRC. Armed conflict in eastern Congo has hampered contact tracing and response efforts, with attacks on treatment centers and health worker deaths complicating containment.rev+1

Parallel Manufacturing and Access Commitments

The trial is funded through an expanded partnership with the Coalition for Epidemic Preparedness Innovations, which has committed up to $50 million to support preclinical work, the phase 1 trial, and simultaneous manufacturing of additional clinical doses. Producing doses before knowing whether the vaccine works is intended to compress timelines so later-stage trials can begin without waiting for a manufacturing run.inkl+2

"Getting Moderna's vaccine candidate into a Phase 1 trial this rapidly is a major step forward," said Richard Hatchett, CEPI's chief executive. If the vaccine is ultimately licensed, Moderna has committed to making at least 500,000 doses available to low- and middle-income countries at access pricing.beckershospitalreview+2

No Quick Fix for the Current Crisis

A phase 1 trial will not alter the course of the current outbreak. It measures only safety and immune response in healthy volunteers, not real-world protection. Phase 1 results are expected around September, at which point the candidate could potentially be added to a WHO-coordinated adaptive phase 3 trial planned in the DRC using ring vaccination among contacts of confirmed cases.inkl+1

Moderna's candidate is not alone. A viral-vector vaccine developed by the University of Oxford and the Serum Institute of India is already in phase 1 testing in the United Kingdom. Meanwhile, WHO has recommended testing the existing Zaire-targeted Ervebo vaccine in a phase 3 trial in the DRC, based on animal data suggesting possible cross-protection against Bundibugyo.rev+2