Three Bundibugyo Ebola vaccine candidates advance with $62M funding boost

Three vaccine candidates targeting the Bundibugyo Ebola virus are moving into accelerated development after receiving $62 million in funding this week—a rare moment of momentum in a region where the outbreak has claimed lives across the Democratic Republic of the Congo and Uganda. As of early June, health authorities in the DRC had confirmed 344 cases and 60 deaths, while Uganda reported 15 cases and one death. The numbers represent a significant downward revision from earlier estimates that had suggested more than 1,000 suspected cases in the region.

The funding push arrives because the world already has two approved Ebola vaccines—Ervebo and Zabdeno/Mvabea—but neither works against the virus currently spreading. Both target the Zaire strain of Ebola, a different pathogen entirely. The Bundibugyo virus has different surface proteins, the very structures that vaccines train the immune system to recognize and attack. This fundamental mismatch means existing vaccines offer little protection, forcing researchers to start largely from scratch. The Coalition for Epidemic Preparedness Innovations is now backing three separate approaches, each with its own timeline and technology.

The first candidate comes from the International AIDS Vaccine Initiative working with the University of Texas Medical Branch. It's a single-dose vaccine using a similar platform to the approved Ervebo shot, and it has already shown promise in macaque monkeys, protecting them against Bundibugyo infection. A WHO expert panel called it the most promising of the three candidates, though human trials remain seven to nine months away. The second candidate is from Moderna, the American pharmaceutical company known for its COVID vaccine. This one uses messenger RNA technology to target the virus's surface glycoprotein, with the new funding expected to support both animal studies and human clinical trials. The third comes from the University of Oxford and India's Serum Institute, built on the same viral vector technology that underpinned the Oxford-AstraZeneca COVID vaccine. This team is further behind—testing is just beginning—but WHO experts suggested human trials could start within two to three months if additional animal data supports moving forward.

The path from promising laboratory results to a vaccine in people's arms remains steep. Each candidate must prove safe and effective in human trials, navigate regulatory approval, scale up manufacturing, and then reach remote populations in regions where health infrastructure is fragile and trust in vaccines may be low. The clinical trials themselves present a particular challenge. Recruiting healthy volunteers for studies in countries far from outbreak zones has proven difficult in the past, complicated by vaccine hesitancy and misinformation. When trials do move to affected regions—where the data that matters most can actually be collected—researchers often face limited medical resources, geographic isolation, and sometimes active conflict.

For now, the outbreak remains controlled primarily through the oldest tools: isolating the sick, protecting healthcare workers, and breaking chains of transmission through careful contact tracing. A working vaccine would transform the response, offering protection to health workers and first responders, and providing a way to shield contacts of confirmed cases. It would also create a defense against future outbreaks of the same virus. But that moment remains months away at best, and the real work of getting a vaccine from the lab into arms in the DRC and Uganda has only just begun.