Lead image for Can a vaccine built for one Ebola virus stop another? WHO is about to find out.
The World Health Organization (WHO) has recommended prioritising the Ervebo vaccine for testing in a clinical trial in the Democratic Republic of the Congo. The vaccine was originally developed to protect against Zaire ebolavirus, the species responsible for the devastating west African epidemic just over a decade ago. It was not designed for the Bundibugyo species responsible for the current outbreak – which raises the question of why scientists are considering it at all.
The current Ebola outbreak was declared a public health emergency of international concern in May 2026. By August 9, there had been 4,402 confirmed cases and 2,013 deaths. All but 21 of these cases were reported in the Democratic Republic of the Congo (DRC), with 20 cases in Uganda and one in France.
These figures make the current outbreak the second-largest Ebola epidemic on record, surpassed only by the west African epidemic of 2014–16, where 11,000 people died.
At present, there are around 75–100 new cases being reported each day. The UN has described it as the fastest-growing Ebola outbreak ever recorded. Tedros Adhanom Ghebreyesus, the director general of the WHO, said the current outbreak is on track to become the world’s largest.
Unfortunately, there is still no clear evidence that the outbreak is coming under control, and the number of infections may still be rising rapidly.
Ebola outbreaks are usually brought under control through a combination of vaccination and public health measures. During an outbreak, vaccines can be particularly effective, especially when used quickly.