New Ebola Vaccine Enters Human Clinical Trials

A new vaccine targeting the strain of Ebola virus which is responsible for killing hundreds of people in the Democratic Republic of Congo this year has started human clinical trials in the U.K.

The experimental vaccine developed by researchers at the University of Oxford, has entered human testing, with researchers hopeful that it might work against the Bundibugyo Ebolavirus strain which is currently in outbreak across the African nation.

The vaccine called ChAdOx BDBV

The trial, led by scientists at the Oxford Vaccine Group and the Pandemic Sciences Institute, will assess whether the vaccine is safe and how strongly it stimulates the immune system. The study will enroll 50 healthy adult volunteers and represents the first clinical evaluation of a vaccine specifically developed against Bundibugyo ebolavirus.

The rapid progression of the vaccine into human testing reflects lessons learned from the COVID-19 pandemic, where adaptable vaccine technologies enabled researchers to respond quickly to emerging infectious threats. ChAdOx BDBV uses Oxford’s chimpanzee adenovirus vector platform, the same technology that was used to develop the Oxford-AstraZeneca COVID-19 vaccine.

The urgency behind the programme comes from a major gap in Ebola preparedness. Although an Ebola vaccine already exists, it does not protect against all Ebola viruses.

The only licensed Ebola vaccine currently available, Ervebo (rVSV-ZEBOV), was developed to protect against Zaire ebolavirus, the strain responsible for the devastating 2014–2016 West African Ebola outbreak that caused more than 11,000 deaths. The vaccine has been highly effective in preventing disease caused by Zaire ebolavirus and has become an important tool during outbreaks through ring vaccination strategies, where people who have been exposed to the virus and their contacts are vaccinated.

However, Ebola is not a single virus. The disease is caused by several different species of viruses within the Ebola virus family, including Zaire ebolavirus, Sudan ebolavirus, and Bundibugyo ebolavirus. These viruses differ genetically, meaning immunity generated against one species does not necessarily provide protection against another.

As a result, Ervebo is not licensed for use against Bundibugyo ebolavirus and is not expected to provide sufficient protection against the strain currently circulating in the DRC.

This has left public health teams responding to the outbreak without access to an approved vaccine specifically matched to the virus causing infections. Instead, outbreak control has relied on rapid diagnosis, contact tracing, infection prevention measures, supportive care, and the development of new medical countermeasures.

The Oxford vaccine programme is one part of a broader effort to address this vulnerability. Researchers hope that, if the Phase I trial demonstrates that the vaccine is safe and produces a strong immune response, further studies could evaluate its ability to protect people during future outbreaks.

Early-stage vaccine trials are designed primarily to establish safety and measure immune responses rather than demonstrate effectiveness. However, the launch of this first human trial represents a significant milestone in expanding Ebola vaccine preparedness beyond a single viral strain.

The ongoing Bundibugyo ebolavirus outbreak has highlighted a longstanding challenge in infectious disease preparedness: vaccines developed against one pathogen variant may not protect against closely related viruses that emerge later. Building a broader portfolio of vaccines could help ensure that future Ebola outbreaks can be met with faster and more targeted responses.

An effective vaccine is approved for the Zaire Ebolavirus strain, but this is ineffective for Bundibugyo and other Ebola strains

The current outbreak has already claimed over 800 lives and sickened over 2,000 people as of the last World Health Organization statistics updated in mid-July.