We guessed wrong about which strain would emerge again
For fifteen years, a vaccine capable of shielding primates from the Bundibugyo strain of Ebola has waited in scientific limbo — developed by a Texas virologist in the shadow of post-9/11 biodefense funding, then abandoned when the market found no profit in it. Now, with hundreds dead in Central Africa and the World Health Organization pointing to this shelved candidate as the best available hope, the world is confronting a familiar reckoning: that the architecture of pharmaceutical incentive was never designed to protect the most vulnerable. A modest infusion of $3.2 million has finally set human trials in motion, but the outbreak does not pause for bureaucratic timelines.
- A Bundibugyo outbreak spreading across Congo and Uganda has already killed roughly 200 people, and the only promising vaccine has never once been tested in a human being.
- The vaccine worked in primates in 2011 — and then sat untouched for fifteen years because no pharmaceutical company saw a viable market in protecting populations too poor to generate profit.
- Scientists cannot even obtain a live sample of the current strain to confirm the vaccine's match, leaving a critical 2 percent of genetic uncertainty unresolved as the death toll climbs.
- CEPI's $3.2 million commitment has unlocked a path to human trials, but regulatory approval could take months — months the outbreak is not willing to wait.
- The researcher who built the vaccine has stepped back, leaving the work to others, able only to watch and hope from a distance.
In 2011, three vaccinated macaques sat in a high-containment island laboratory off the Texas coast while their unvaccinated counterparts bled, wasted, and died from Bundibugyo Ebola. The vaccinated animals showed no symptoms at all. It was a striking result — and for fifteen years, almost no one acted on it.
Thomas Geisbert, a virologist at the University of Texas Medical Branch in Galveston, had built his Ebola vaccine program out of post-9/11 biodefense funding, demonstrating as early as 2003 that a single injection could protect monkeys from the virus. Pharmaceutical companies were unmoved. There was no commercial logic in Ebola vaccines. His work continued quietly, expanding to cover multiple strains — but Bundibugyo, which had caused only a handful of small outbreaks, was initially left aside. When he finally modified a vaccine specifically for it in 2011, the primate results were promising. Then the world moved on.
The 2013–2016 West African epidemic changed the calculus for the Zaire strain. With 28,600 infections and 11,300 deaths, urgency materialized, money followed, and Merck's Ervebo — built partly on Geisbert's foundational research — eventually reached the field. Geisbert was named among Time's Ebola fighters. But Bundibugyo remained the overlooked strain, assumed too rare to resurge. "We guessed wrong," he now says.
In 2024, Bundibugyo returned with force. The current outbreak in Congo and Uganda has infected hundreds and killed approximately 200. The WHO identified Geisbert's vaccine — essentially the same rVSV platform as Ervebo, adapted for this strain — as the most viable candidate available. A 2023 study confirmed that vaccinated monkeys remained protected even after direct exposure, a result critical for ring vaccination strategies. But that study was also the last meaningful step forward. Without an active outbreak, there had been no funding. Without funding, there had been no trials.
Courtney Woolsey, who led that 2023 study, described the structural problem without euphemism: the people most at risk from these outbreaks are not profitable patients. The vaccine has never entered a human body. It has never cleared the safety and efficacy trials required for approval.
Now, the Coalition for Epidemic Preparedness Innovations has committed $3.2 million to begin manufacturing preparations and initiate human trials, with the International AIDS Vaccine Initiative overseeing production. It is a start — but approval remains months away, and an unresolved uncertainty lingers: resource constraints in the DRC have prevented scientists from obtaining a live sample of the current strain. The circulating virus appears roughly 98 percent similar to earlier versions, but that remaining margin is unknown territory. Geisbert has passed the work to younger colleagues. He can only wait, and hope that something he built fifteen years ago — or something someone else builds now — arrives in time.
In 2011, three crab-eating macaques sat in a high-containment laboratory on an island off the Texas coast, having been deliberately exposed to a newly discovered strain of Ebola called Bundibugyo. The unvaccinated monkeys developed fever, lost weight, bled from their rectums and noses. Two-thirds of them died. The three that had received an experimental vaccine showed no symptoms at all.
Thomas Geisbert, a virologist at the University of Texas Medical Branch in Galveston, had developed that vaccine years earlier as part of a post-9/11 defense initiative. The U.S. Army had funded his work in the early 2000s, concerned that terrorists might weaponize Ebola or similar pathogens. His first major success came in 2003, when he demonstrated that a single injection could protect monkeys from the virus. But when he published those findings, pharmaceutical companies showed little interest. There was no money in it. Ebola vaccines weren't profitable.
Geisbert expanded his work to test whether a single vaccine could protect against multiple strains of Ebola. In 2009, he published results showing success against three of the four known human strains. Then came the 2013-to-2016 West African epidemic. The Zaire strain infected 28,600 people and killed 11,300. Suddenly, the world wanted an Ebola vaccine. Merck, building partly on Geisbert's research, developed Ervebo. It was deployed in "ring vaccination" campaigns—vaccinating contacts of infected people to create a protective buffer. The strategy worked. Geisbert made Time magazine's list of "Ebola fighters" in 2014.
But his initial studies had omitted one strain: Bundibugyo. It had caused only three outbreaks and had lower fatality rates than Zaire. The 2012 outbreak in the Democratic Republic of Congo killed 30 people over three months before being contained. Geisbert assumed it was the least likely to emerge again. "We guessed wrong," he now says. Concerned about the gap in his research, he modified a vaccine specifically for Bundibugyo in 2011—the same year his primate studies showed it worked. He also tested whether existing Ebola vaccines could protect against Bundibugyo. They couldn't, not completely.
Then, in 2024, Bundibugyo returned. The current outbreak in Congo and Uganda has infected hundreds of people and killed approximately 200. The World Health Organization, drawing on its experience with Ervebo's success, identified Geisbert's Bundibugyo vaccine as the most promising candidate available. It is essentially "Bundibugyo Ervebo," he explains—using the same rVSV platform that had proven effective against other strains. A 2023 study showed that vaccinated monkeys remained protected even after exposure to the virus, a crucial finding for ring vaccination to work. But that study was the last significant development. Without an outbreak, there was no urgency. Without urgency, there was no funding.
Courtney Woolsey, the lead author of that 2023 paper and an assistant professor at Geisbert's institution, put it plainly: "Nobody really makes money off these vaccines. There are funding barriers to advance these vaccines where people likely aren't going to make money." The vaccine has never been tested in humans. It has never gone through the safety and efficacy trials required for approval. It has sat on a shelf for fifteen years.
Now, with hundreds dying, the Coalition for Epidemic Preparedness Innovations has offered $3.2 million to prepare manufacturing materials and begin human trials. The International AIDS Vaccine Initiative in New York will oversee production. Even with this support, approval could take months—months during which the outbreak continues. There is also an unknown risk: scientists have been unable to obtain a live sample of the current Bundibugyo strain for testing due to resource constraints in the DRC and the logistical complexity of transporting refrigerated blood to the United States. The current strain appears to be about 98 percent similar to previous versions, but that remaining 2 percent is uncertainty. "Nothing's foolproof," Geisbert says. He has handed the work to others now. All he can do is wait and hope—whether his vaccine works, or someone else's does.
Citações Notáveis
There just wasn't a global market for an ebola vaccine. It's not a moneymaker, nobody really wanted to pick it up.— Thomas Geisbert, virologist
Nobody really makes money off these vaccines, so there are funding barriers to advance these vaccines where people likely aren't going to make money.— Courtney Woolsey, assistant professor, University of Texas Medical Branch
A Conversa do Hearth Outra perspectiva sobre a história
Why did this vaccine sit untested for so long if the animal trials were successful in 2011?
Because there was no market. Ebola is rare, unpredictable, and doesn't strike wealthy countries. Pharmaceutical companies need profit incentives. Without an active outbreak creating demand, there was no reason for them to invest in manufacturing, testing, or regulatory approval.
But Geisbert's work on other strains led to Ervebo, which worked. Why didn't that success translate to funding for Bundibugyo?
Timing. The 2012 Bundibugyo outbreak was small and contained quickly. If it had happened after the massive 2013-2016 West African epidemic, when the world was desperate for any Ebola vaccine, companies might have been more willing to develop a Bundibugyo version. Instead, it was forgotten.
So the vaccine could have been ready years ago?
Potentially. The animal data was solid. The platform—rVSV—had already proven safe and effective in humans through Ervebo. The regulatory pathway could have been expedited. But without a crisis, there's no political will, no funding, no urgency.
What's the risk now in rushing it to human trials?
The main unknown is whether the current strain is different enough that the vaccine won't work. Scientists can't test against live virus because they don't have samples. They're working from genetic sequences that show 98 percent similarity to old strains. That 2 percent gap is where doubt lives.
How long until people can actually be vaccinated?
Months, at minimum. They're just now starting to prepare manufacturing materials. Safety trials take time. Even if everything goes perfectly, you're looking at a race against an outbreak that's already spreading.
What does Geisbert think will happen?
He's handed it off. He hopes it works—his vaccine or someone else's. But he's also realistic. He says Bundibugyo will probably emerge again. Next time, maybe they'll be ready.