The World Health Organization (WHO) has issued new emergency guidance limiting the use of the licensed Ervebo vaccine during outbreaks of Bundibugyo virus disease to research protocols only.
The organisation made this known in a statement on Tuesday, saying the guidance followed an extraordinary meeting of the Strategic Advisory Group of Experts on Immunisation held on 19 August 2026.
WHO said Ervebo should currently be used against Bundibugyo virus only within a research protocol to generate evidence on its effectiveness, rather than through broader routine outbreak vaccination.
According to the organisation, a ring vaccination randomised controlled trial would be the most robust approach for determining Ervebo’s efficacy against Bundibugyo virus disease among affected populations.
It said broader vaccine use before trial results would require a comprehensive risk-mitigation plan addressing potential risks during outbreak response and ensuring prompt monitoring of recipients’ health outcomes.
“WHO continues recommending preventive Ervebo vaccination for healthcare and frontline workers in Ebola virus priority areas with previous Ebola disease outbreaks,” the organisation said.
In its guidance, WHO also emphasised the preventive vaccination policy.
“In areas affected by the current Bundibugyo outbreak, Ervebo should only support outbreak response through research protocols, including ring trials or observational vaccine-effectiveness studies,” WHO said, stressing that evidence generation remains essential.
“Such studies could provide additional evidence about the potential performance of Ervebo against Bundibugyo virus during ongoing outbreaks,” it added.
The statement said those findings could inform future policy and vaccine recommendations.
WHO said off-label use might exceptionally be considered where research is not feasible, provided reliable vaccination records can track recipients and their subsequent health outcomes over time to support safety monitoring.
It urged accelerated development and rigorous evaluation of vaccines specifically targeting Bundibugyo virus disease, as well as post-exposure prophylaxis products and other needed countermeasures for outbreak preparedness and response.
The organisation also called for stronger coordination among partners supporting the Democratic Republic of Congo and other countries considering Ervebo within research protocols to ensure consistent implementation and timely evidence sharing.
It recommended developing and sharing master protocols for ring vaccination trials and high-quality observational studies to ensure coordinated evidence generation during the current outbreak and future emergency responses.
