WHO suggests trial for Ebola vaccine against Bundibugyo virus

The World Health Organisation (WHO) has advised that a vaccine called Ervebo should be prioritized for a clinical trial against the Bundibugyo virus disease in the Democratic Republic of Congo (DRC).

This recommendation came after early animal study results showed that the vaccine might offer some protection against the disease and could help reduce deaths.

WHO’s Technical Advisory Group on Candidate Vaccine Prioritisation made the suggestion at its third meeting on 31 July. They reviewed the available information on the vaccine’s safety, effectiveness, availability, and feasibility.

This news arrives as the DRC deals with an outbreak of Ebola disease caused by the Bundibugyo virus, which was officially declared on 15 May 2026.

As of 30 July, WHO reported 3,605 confirmed cases and 1,587 deaths from this outbreak in the DRC.

Why Ervebo is being considered

The advisory group’s recommendation is important because Ervebo was made specifically for Ebola virus disease caused by the Ebola Zaire virus, not the Bundibugyo virus.

According to WHO, the group had initially advised against using Ervebo outside of carefully controlled research settings. This was due to uncertainty about how effective it is against Bundibugyo virus disease.

But now, early animal study data suggests that Ervebo might provide some protection against Bundibugyo virus disease, especially in reducing deaths.

This new evidence led the advisory group to recommend that Ervebo should be prioritized for a clinical trial to see how well it works against the disease.

What is the Bundibugyo virus?

The Bundibugyo virus causes Ebola disease. It is different from the Ebola virus that Ervebo was designed to protect against.

The outbreak of Bundibugyo virus disease in the DRC is the first of its kind in the country. WHO says there is no licensed vaccine or specific treatment for Bundibugyo virus disease at this time.

The disease is very serious, and past Bundibugyo virus disease outbreaks have shown case fatality rates between 30 and 50 per cent, according to WHO.

Safety concerns

WHO reports that the advisory group found no safety issues with using Ervebo among people who had contact with confirmed cases during a Bundibugyo virus disease outbreak.

However, the experts pointed out that they still do not know how effective the vaccine is against Bundibugyo virus disease or if it can prevent transmission.

They recommended that these important questions be looked at through clinical research.

WHO stated that a vaccine made specifically for the Bundibugyo virus would be the best choice, even though there is currently no early data on such candidates.

The advisory group also stressed the need to ensure large-scale vaccine production and access if future evidence shows that a vaccine can effectively protect affected populations.