Inside the race to develop a new Ebola vaccine

Moderna’s mRNA – Moderna, supported by up to $50 million from CEPI, is accelerating an investigational mRNA vaccine targeting the rare Bundibugyo virus driving Ebola outbreaks in the Democratic Republic of the Congo and Uganda—aiming to reach phase 1 trials within months as re

In the middle of an Ebola outbreak that is already spreading through parts of the Democratic Republic of the Congo and Uganda, Moderna is trying to close a specific, painful gap: a vaccine for the Bundibugyo virus species.

The company says its investigational mRNA candidate is moving with urgency. with support of up to $50 million from the Coalition for Epidemic Preparedness Innovations (CEPI). Moderna’s goal is to advance the program toward early human testing—an early phase safety trial—within months. if regulatory review and approvals go the way the company and CEPI are planning.

“The programme has been designed to move with urgency,” Moderna said in a statement shared with Scientific American. Moderna said it is working to accelerate the candidate into a phase 1 clinical trial “in the coming months,” subject to regulatory review and approvals.

The stakes are not theoretical. Ebola vaccines exist, but they are not designed to cover every species of Ebola virus that can cause deadly disease in humans. Bundibugyo is one of those missing pieces.

CEPI’s commitment is also unusually broad for a single outbreak response. CEPI has committed up to $60 million to develop three Bundibugyo vaccine candidates: Moderna’s mRNA vaccine; a candidate from IAVI (formerly the International AIDS Vaccine Initiative); and a University of Oxford candidate manufactured by the Serum Institute of India. Each uses a different technology.

mRNA vaccines use genetic instructions to make the body produce a viral protein. The IAVI candidate uses a recombinant vesicular stomatitis virus—a weakened version of a virus that can infect livestock—as a vector to deliver genetic instructions for a Bundibugyo virus protein. Oxford’s ChAdOx platform uses a modified chimpanzee adenovirus as a delivery vehicle.

CEPI deputy CEO Aurélia Nguyen says the organization moved quickly because the outbreak is “deeply concerning” and no approved vaccine is available. She said CEPI mobilized resources just over two weeks after the DRC announced the outbreak in mid-May. to advance vaccine candidates that could help control the epidemic.

Nguyen said CEPI selected the three candidates after a global review and consultations with the World Health Organization. the Africa Centers for Disease Control and Prevention. Gavi. the Vaccine Alliance. and the affected countries. “Having multiple shots on goal increases our chances of developing a successful vaccine,” Nguyen says.

For Moderna, CEPI support will fund preclinical testing and a phase 1 clinical trial. Moderna said the funding will also allow it to manufacture doses of its vaccine in parallel, so larger phase 2/3 trials can begin quickly if phase 1 data are promising.

For IAVI, CEPI has committed up to $3.2 million in initial funding for work needed to prepare a master virus seed stock, described as a starting material for vaccine manufacturing.

For Oxford and the Serum Institute of India, CEPI promised up to $8.6 million for preclinical testing, vaccine development and manufacturing of clinical-grade doses.

If early trials are successful, Nguyen said CEPI expects to work with partners to support late-stage trials that could generate data for regulatory agencies to issue an emergency use authorization or licensure.

The reason Bundibugyo has been a tougher target is partly historical. Scientists first identified Bundibugyo virus in Uganda in 2007. but it had caused far fewer known Ebola outbreaks than the original Ebola virus species—formerly Zaire virus—that drove the devastating 2013 to 2016 West African epidemic and later outbreaks in the DRC.

That history shaped vaccine development. Most Ebola countermeasure work has focused on Ebola virus. which has caused larger outbreaks than Bundibugyo and was also treated as a potential biological warfare threat. The licensed Ebola vaccine Ervebo is approved for the Ebola virus, not Bundibugyo virus.

Amesh Adalja. a senior scholar at the Johns Hopkins Center for Health Security. said the current outbreak shows the consequences of that narrower focus and why rarer Ebola species cannot be ignored. “Though Bundibugyo has historically been a lower priority because it has caused fewer known outbreaks. all of these are deadly diseases. All of these deserve some level of attention,” Adalja said.

Nguyen said CEPI’s investments before this outbreak had similarly focused on members of the filovirus family—orthomentum threats that include orthoebolaviruses and related viruses—judged to pose greater epidemic risk and lacking sufficient countermeasures. She said those included Ebola virus, Marburg virus and Sudan virus, another orthoebolavirus. Since Ebola virus was identified in 1976. she said there have been more than 50 outbreaks of different filoviruses. but Bundibugyo had caused only two before the current outbreak.

Before CEPI funding Bundibugyo vaccine candidates. Nguyen said CEPI had already begun investing in broader “all-in-one” vaccines that could potentially provide protection across a range of filoviruses. including Bundibugyo. She said those programs remain at an early stage. but CEPI is assessing whether any of these vaccine designs could be tested during the current outbreak.

The push toward Bundibugyo vaccines is also drawing attention to what mRNA can do for public health when outbreaks don’t match yesterday’s playbook.

Moderna said its Bundibugyo candidate builds on more than a decade of mRNA platform research and years of work designing mRNA vaccines against filoviruses. It said that as soon as the relevant Bundibugyo ebolavirus genetic sequence became available. it was able to “rapidly design and begin developing multiple vaccine candidates” using its established platform.

Nguyen said the advantage of the mRNA approach is that the underlying platform can remain largely the same while researchers change the genetic sequence encoded by the vaccine. She said Moderna’s platform delivers genetic instructions for the Bundibugyo glycoprotein—a protein molecule found on the virus—that tells the body’s own cells to produce it.

mRNA vaccines do not require manufacturers to grow large quantities of live virus. Moderna said the same basic production system can be adapted for different vaccines by changing the genetic instructions the vaccine carries. and that flexibility can shorten the time needed to design and produce a candidate.

Adalja said mRNA vaccines may not be the best vaccine technology for every pathogen, but he said their speed makes them important for emerging threats.

Nguyen connected the current urgency to what the COVID-19 pandemic changed in vaccine development. She said the pandemic provided an opportunity to validate mRNA and other adaptable vaccine platforms and allowed the wider vaccine-development chain to be activated more quickly during an outbreak.

She said all three Bundibugyo vaccine technologies CEPI is funding use validated platforms. approved vaccine backbones or established manufacturing processes that can be adapted to different pathogens. And she said coordination has moved faster compared with the early COVID response: global health principals convened less than a week after the current Ebola outbreak was declared. and she said African research and leadership have been central to the response.

But speed is not the same as instant availability.

Moderna said its mRNA system can speed up early vaccine development because the basic design and manufacturing process can be reused while the genetic instructions inside the vaccine are changed to match a new virus. Still. the company said key steps still require time and cannot be bypassed: preclinical studies; safety evaluation in humans; immune-response studies; regulatory review; evaluation of clinical trial sites; ethical approvals; and data generation for any emergency-use or licensure pathway.

Nguyen said vaccine development remains complex, even when stages are run in parallel. She pointed to technical hurdles, including problems producing trial materials or unexpected safety signals in studies.

Field trials in the eastern DRC, she said, could also be complicated by geopolitical conflict, weak health systems, misinformation, and population movement—factors that could affect recruitment and data collection.

Moderna has not given a firm timeline beyond saying it is working toward phase 1 testing in the coming months. Whether the vaccine candidate will be deployed in response to the current Ebola outbreak depends. Moderna said. on the pace of development. emerging data. regulatory pathways. and the operational realities of conducting studies and deploying vaccines during an epidemic.

“Even if the candidate is not available in time to materially affect the current outbreak, advancing it could substantially strengthen preparedness for future Bundibugyo ebolavirus outbreaks,” Moderna said.

Right now, the race is less about promises and more about whether the pieces can move fast enough—science, regulation, manufacturing, and field conditions—before the outbreak writes a clock of its own.

Ebola Bundibugyo Moderna CEPI mRNA vaccine phase 1 trial Democratic Republic of the Congo Uganda Ervebo IAVI Oxford ChAdOx Serum Institute of India