Bundibugyo ebolavirus is a species of Ebola virus that was first identified in the Bundibugyo district of western Uganda. It causes severe and often fatal viral haemorrhagic fever. Earlier this year the WHO declared a Public Health Emergency of International Concern (PHEIC) in relation to the outbreak of Ebola disease caused by the Bundibugyo virus. There are currently no widely licensed vaccines or specific therapeutics for Bundibugyo virus disease. It is now the fastest-growing outbreak of Ebola on record and has caused more than 2,000 deaths in the Democratic Republic of Congo at the time of writing.
After the emergency was declared on 17th May 2026, scientists at the University of Oxford sprang into action and developed a new vaccine using the same technology as the Oxford/AstraZeneca Covid vaccine. They registered their Phase Ia study with ISRCTN and began enrolling participants in the UK just 8 weeks later in July. This vaccine is the first out of the four Ebola vaccines under development to enter clinical trials. This impressive feat was reported across many news outlets including BBC News.
Phase I trials test medical products in humans for the first time. Phase Ia trials test single doses on healthy volunteers, using increasing doses on different groups of participants to assess safety limits and tolerability. Phase Ib trials involve repeated dosing over weeks to confirm safe dosing schedules for later studies.
The Phase Ib study of the Oxford vaccine has also just started enrolling in Uganda and was registered with the Pan African Clinical Trials Registry. Moderna have also started a trial of their mRNA-based vaccine in Canada, which was registered at ClinicalTrials.gov.
The only currently licenced Ebola vaccine, Ervebo, is approved for use in outbreaks caused by the closely related and more common Zaire strain of Ebola. A panel held by the WHO has now called for a Phase III trial of Ervebo to investigate its effectiveness against the current Bundibugyo strain.
Ervebo uses a recombinant vesicular stomatitis virus (rVSV) as a vector. Two Bundibugyo vaccines are now being developed based on this platform: one by the International AIDS Vaccine Initiative, and the other by Public Health Vaccines, a US-based biotechnology company. At the time of writing both of these vaccines are in preclinical development and have yet to be tested in clinical studies in humans.
Alongside the vaccine trial news, The Guardian also reported on the PARTNERS trial, a WHO-sponsored platform trial of potential treatments for filovirus diseases including Ebola, which has opened with two drugs on its books: the antiviral remdesivir and the monoclonal antibody MBP134. The trial was first registered with ISRCTN in 2024 and was updated in 2026 in response to the Bundibugyo outbreak.
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