Thomas Geisbert has been waiting for a moment like this since 2013—the year he published research on a vaccine candidate for the rare Bundibugyo Ebola strain. That moment may have finally arrived. As the Democratic Republic of Congo grapples with an outbreak of this elusive virus that has claimed more than 130 lives, scientists are racing to transform years of shelved research into treatments and vaccines that could save lives within months rather than years.
This is the 17th Ebola outbreak in DR Congo, but only the third caused by the Bundibugyo strain, making it a medical frontier where few solutions exist. Unlike the more common Zaire strain, which claimed 11,300 lives during West Africa's catastrophic 2014–2016 outbreak, Bundibugyo has no approved vaccines or treatments. The market for such drugs is small and historically unprofitable—what pharmaceutical companies call a "non-money-maker"—which explains why Geisbert's promising Bundibugyo vaccine candidate remained on a shelf for over a decade before this outbreak demanded action.
Now there is urgency. Geisbert, a virologist at the University of Texas Medical Branch at Galveston, designed a single-injection vaccine targeting Bundibugyo that has shown protection against the virus in monkey trials. He estimates that a pharmaceutical partner could move from development to deployment in as little as six or seven months—a fraction of the time that typically locks in these efforts. The template exists: MSD, known as Merck in North America, managed to roll out its Zaire-targeting Ervebo vaccine in around nine months during the 2014 crisis. That vaccine has proven 84 percent protective against Zaire. But whether a company will step forward for Bundibugyo remains uncertain.
The search is expanding on multiple fronts. Chinese researchers published findings this week in the journal PNAS describing a newly developed mRNA vaccine—using the same technology that powered COVID-19 vaccines—that targets three major Ebola strains including Bundibugyo. Yet the approach carries logistical challenges. Connor Bamford, a virologist at Queen's University Belfast, cautioned that mRNA vaccines are expensive and require ultralow-temperature storage, constraints that could severely limit deployment across Africa's healthcare infrastructure. Geisbert added that the Chinese vaccine has only been tested on mice, and results in rodents frequently fail to translate to primates or humans.
Oxford University researchers are pursuing a different path: a viral vector vaccine called ChAdOx1 BDBV, developed in collaboration with the Serum Institute of India, the world's largest vaccine maker. "We are working through the logistics at pace," Teresa Lambe, head of vaccine immunology at the Oxford Vaccine Group, told journalists, while acknowledging that a precise timeline cannot yet be given.
On the treatment front, a WHO-sponsored trial of two experimental Bundibugyo therapies could launch in affected areas imminently. One candidate is remdesivir, an antiviral made by Gilead that has been tested in humans for Zaire but not Bundibugyo. Intriguingly, Geisbert's laboratory work suggests remdesivir shows "stronger in vitro data against Bundibugyo than it does for Zaire"—a finding that could accelerate trials. Amanda Rojek, an Oxford researcher involved in the treatment effort, expressed confidence about the pace of preparation: "We're in a really strong position to quickly launch trials."
The DR Congo outbreak has transformed what was once a fringe medical challenge into an urgent global priority. Whether years of shelved research can now translate into deployed treatments within months will define the response to this crisis.