WHO recommends Phase III trial of Ebola vaccine against Bundibugyo virus

The World Health Organisation (WHO) has recommended a Phase III trial of an Ebola vaccine to test whether it can protect against Bundibugyo virus disease.

WHO Director-General, Tedros Ghebreyesus, disclosed this in a video posted on his official X account on Thursday.

Ghebreyesus said two vaccines specifically developed against the Bundibugyo virus had entered Phase I safety trials in humans. At the same time, new animal studies had shown promising evidence that Ervebo, an Ebola vaccine, could also provide cross-protection against the virus.

He said the findings prompted WHO to recommend Ervebo for inclusion in a Phase III trial, which the organisation hopes to begin as soon as possible.

However, it is not yet known whether Ervebo can protect humans against Bundibugyo virus disease.

Mr Ghebreyesus said the Phase III trial would help establish whether the vaccine is safe and effective and could provide evidence needed to make it available for the current outbreak and future outbreaks.

No licensed vaccines

The development comes as the Bundibugyo virus outbreak in the DRC has become the second-largest Ebola outbreak on record.

As of Thursday, the country had recorded 4,449 confirmed cases and 2,061 deaths across five provinces and 53 health zones, according to the WHO.

The health agency said the outbreak was spreading faster than any previous Ebola outbreak at the same stage and could surpass the 2014–2016 West African outbreak, which remains the largest on record, with more than 28,000 cases and 11,000 deaths reported in Guinea, Liberia and Sierra Leone.

Bundibugyo virus is one of the viruses in the Ebola family that can cause severe and often fatal disease in humans.

Unlike Ebola virus disease caused by the Ebola virus, there is currently no licensed vaccine specifically approved for the prevention of Bundibugyo virus disease.

WHO said in June that Ervebo, the only licensed and WHO-prequalified Ebola vaccine, is approved for Ebola virus disease but not for Bundibugyo virus disease.

The current outbreak was first detected in the DRC in May, following an unexplained cluster of deaths in Ituri Province that was investigated. Laboratory testing confirmed Bundibugyo virus disease, prompting the DRC government to declare its 17th Ebola outbreak.

Uganda also confirmed imported cases linked to the outbreak in the DRC. WHO subsequently determined that the outbreak in the two countries constituted a Public Health Emergency of International Concern.

Previous Bundibugyo virus outbreaks have had case fatality rates between 30 and 50 per cent, according to the WHO.

PREMIUM TIMES reported on 9 August that WHO had already recommended Ervebo for evaluation in a randomised clinical trial after reviewing evidence suggesting that it could provide some protection against Bundibugyo virus.

Treatment advancement

Mr Ghebreyesus also disclosed progress in research into treatments for Bundibugyo virus disease.

He said a WHO-sponsored partners trial had reached 100 patients.

The trial is assessing potential treatments for the disease and is intended to generate evidence on which therapies can improve outcomes for infected patients.

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Mr Ghebreyesus said the milestone showed that research could be mobilised rapidly and responsibly even during a difficult outbreak.

He called on partners to support and accelerate the vaccine trial, while emphasising that the response requires collaboration among the DRC government, WHO, Africa Centres for Disease Control and Prevention (CDC) and other partners.