No Immediate Vaccine Available for Bundibugyo Ebola Outbreak in Democratic Republic of Congo
A vaccine will not be available anytime soon to help contain the Ebola outbreak currently affecting the Democratic Republic of Congo.
No vaccine is currently available for the Bundibugyo Ebola outbreak in DRC, with promising candidates still months away.
Health officials say there are no approved vaccines designed specifically for the Bundibugyo species of Ebola, the strain believed to have caused 139 deaths so far. According to global health authorities, the leading vaccine candidate remains months away from being available, with estimates ranging from six to nine months before doses can be produced.
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Speaking at a recent briefing, Vasee Moorthy, senior adviser on research and development at the World Health Organization, said efforts are “fully activated to accelerate research and development for medical countermeasures in this context.”
Focus Shifts to Treatment and Case Detection
While vaccine development continues, health officials say immediate priorities include establishing treatment centers, improving case detection, and ensuring infected individuals receive proper care.
The outbreak has already infected hundreds of people. Traditionally, Ebola control efforts depend heavily on identifying cases, tracing contacts, and isolating infected individuals. However, experts warn that the current response faces additional challenges, including militia activity, funding reductions, and political instability in the region.
Existing Ebola Vaccines Do Not Target Bundibugyo
Four species of Ebola are known to infect humans. Although two vaccines currently exist, neither was developed to protect against the Bundibugyo strain driving the present outbreak.
One of the available vaccines is Merck’s Ervebo, which is approved in the United States and was designed to combat the Zaire strain responsible for the 2014-2016 West African Ebola outbreak, the largest recorded outbreak to date.
Moorthy explained that the most promising vaccine candidate uses the same underlying technology as Ervebo but has been specifically adapted to target Bundibugyo Ebola.
Research conducted in 2013 by Thomas Geisbert, professor of microbiology and immunology at the University of Texas Medical Branch and a contributor to the development of Ervebo, demonstrated that an experimental Bundibugyo-specific vaccine successfully protected monkeys.
Despite those results, the vaccine has never been produced according to standards required for human clinical testing.
“The problem we have is the same story as in the West African epidemic. We got a great vaccine - we don’t have a good clinical grade lot” that can be used in humans, Geisbert said. He estimated that process could take eight to nine months.
Additional Vaccine Candidates Under Development
Another potential vaccine is being developed using the same platform employed for AstraZeneca’s COVID vaccine. The project involves collaboration between specialists from the University of Oxford and the Serum Institute of India.
“They are manufacturing that as we speak, but there is no animal data to support that,” Moorthy said. “It is possible that doses of that could be available for clinical trial in two to three months, but there is a lot of uncertainty about that, and it will depend on the animal data as to whether that is considered a promising candidate.”
The Coalition for Epidemic Preparedness Innovations (CEPI) is simultaneously supporting multiple development pathways. The organization is coordinating preclinical research, modeling efforts, and manufacturing support to help countries move quickly into clinical trials once candidates are ready.
“All along the line we have to pay really special attention to safety and we need to be able to explain to the public and countries what we’re doing and why we’re doing this,” said Nicole Lurie, CEPI’s executive director for preparedness and response.
Debate Over Existing Vaccines and Emerging Treatments
Public health officials initially considered whether the Ervebo vaccine could be used despite not being designed for Bundibugyo Ebola. Geisbert described its potential effectiveness as a “coin flip” regarding cross-protection.
Merck stated that decisions about deploying vaccine stockpiles are made by the International Coordinating Group on Vaccine Provision.
Limited animal research has suggested that a vaccine designed for the Zaire strain may provide some protection against Bundibugyo Ebola in monkeys. However, the study involved too few subjects to produce definitive conclusions. A Merck spokesperson emphasized that available data remain limited and that the studies were not conducted in humans.
Experimental Antibody Treatments Offer Potential
Alongside vaccine research, investigators are evaluating treatment options.
One leading candidate is MBP134, a monoclonal antibody treatment developed by Mapp Biopharmaceutical Inc. Designed as a pan-ebolavirus therapy, it was originally intended to protect against the Sudan strain of Ebola but has demonstrated the ability to target multiple Ebola variants and has undergone early human testing.
In 2022, the U.S. federal government awarded a $110 million contract to support development and potential procurement of the treatment through the Administration for Strategic Preparedness and Response.
Emily Hilliard, spokeswoman for the Department of Health and Human Services, said the government is coordinating delivery of an experimental antibody treatment “for use in high-risk Americans exposed to the virus.”
Meanwhile, Satish Pillai, incident manager for the Centers for Disease Control and Prevention’s Ebola response, said during a Wednesday briefing that “there are active discussions” regarding the deployment of monoclonal antibody products to affected countries.
Regeneron Evaluates Inmazeb for Current Outbreak
Another possible treatment option is Regeneron Pharmaceuticals’ approved antibody cocktail, Inmazeb.
Originally developed in response to the West African Ebola outbreak, one of the three antibodies included in the treatment demonstrated activity against previous Bundibugyo Ebola strains during laboratory testing.
“We are working to confirm activity against the current strain and are in contact with the U.S. Government to determine whether and how to deploy this antibody in this current outbreak,” spokeswoman Alexandra Bowie said in an email.
