Scientists at Oxford University are working against the clock to produce an experimental vaccine for the rare strain of Ebola ravaging the Democratic Republic of Congo, as the World Health Organization raised its risk assessment for the outbreak from high to very high — a stark escalation that has injected fresh urgency into efforts to get ahead of a virus that has already claimed 177 lives from 750 suspected cases.
The Oxford team says doses of the vaccine could be ready for clinical trials within two to three months, though researchers are careful to stress that significant uncertainty remains. Animal testing is now underway, and the results will determine whether the candidate advances to human trials.
“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,” a WHO spokesman said, noting that animal data would be essential before the vaccine could be considered a credible research candidate for Bundibugyo Ebola.
The Bundibugyo strain sits at the heart of what makes this outbreak so difficult to contain. Of the six known species of Ebola virus, only three are responsible for large human outbreaks, and Bundibugyo is among the least studied. It has caused just two previous outbreaks — in Uganda in 2007 and in DR Congo in 2012 — and had not been detected in over a decade before the current emergency. It kills approximately one in three of those it infects, and unlike the more common Zaire strain, for which an approved vaccine exists, Bundibugyo has no proven immunisation.
The vaccine Oxford is developing draws on the same platform the team built during the Covid-19 pandemic — a highly adaptable technology known as ChAdOx1 that can be rapidly reconfigured to target different pathogens. During the pandemic it carried genetic code from the coronavirus; it has now been loaded with genetic material from the Bundibugyo strain. The mechanism uses a common cold virus that normally infects chimpanzees, genetically modified to make it safe for humans, which then delivers instructions to cells on how to recognise and fight off Ebola. The vaccine does not cause infection or trigger Ebola symptoms — it simply trains the immune system to mount a defence.
Prof Lambe, the Calleva Head of Vaccine Immunology at the Oxford Vaccine Group, said speed was the overriding priority.
“People are worried about this outbreak, generally, you prepare for the worst case scenario — hopefully contact tracing and quarantine is all that’s needed, but we can’t take our foot off the gas,” she told the BBC.
She added that the Serum Institute of India had been lined up to mass-produce the vaccine once Oxford could supply medical-grade material. “Once we get starting material to them they can go fast and they can go big,” Lambe said.
The WHO declared the outbreak a public health emergency of international concern earlier this week, while stressing that it had not reached pandemic status. The wider regional risk is now assessed as high, though the international risk remains low. Those assessments can change quickly — as the upgrade inside DR Congo from high to very high has already demonstrated.
If the vaccine does advance to use, it would not be deployed in the way Covid vaccines were during the pandemic. Ebola immunisation relies instead on a technique called ring vaccination, targeting only those at highest risk — close contacts of confirmed cases and healthcare workers treating infected patients, who are themselves highly vulnerable to transmission through contact with bodily fluids.
The Oxford team is not working from a standing start. Researchers had already been developing related vaccines for the Sudan species of Ebola and for Marburg virus, giving them a foundation of knowledge and laboratory infrastructure they are now directing towards Bundibugyo. Whether that head start will be enough to put a viable vaccine in the field before the outbreak worsens is the question driving the work in Oxford’s laboratories right now.
By: Andrews Kwesi Yeboah