Uganda and WHO Launch Historic First-Ever Ebola Sudan Vaccine Trial in Record Time
“This is a critical achievement toward better pandemic preparedness and saving lives when outbreaks occur,” said Dr. Tedros Adhanom Ghebreyesus, WHO Director-General.

In a global first, Uganda’s Ministry of Health, the World Health Organization (WHO), and international partners have launched the first-ever vaccine trial for Ebola Sudan virus, achieving unprecedented speed for a randomized vaccine trial in an emergency.
The landmark trial aims to evaluate the clinical efficacy of a candidate recombinant vesicular stomatitis virus (rVSV) vaccine against Ebola Sudan virus, a strain with no licensed vaccine to date. The trial launch in Kampala marks a significant milestone in global pandemic preparedness and future outbreak response.
Rapid Response to Contain Ebola Sudan Outbreak
Ugandan principal investigators from Makerere University and the Uganda Virus Research Institute (UVRI), with WHO's support, prepared the trial in just four days following the outbreak confirmation on 30 January 2025. The breakthrough speed was possible due to advanced research preparedness and strict adherence to international regulatory and ethical standards.
“This is a critical achievement toward better pandemic preparedness and saving lives when outbreaks occur,” said Dr. Tedros Adhanom Ghebreyesus, WHO Director-General.
“This was only possible due to the dedication of Uganda’s health workers, community engagement, and collaboration between the Ministry of Health, Makerere University, UVRI, and WHO’s global research network. We also thank IAVI for donating the vaccine, CEPI, EU HERA, and Canada’s IDRC for funding, and Africa CDC for further support.”
Global Collaboration for Vaccine Trial
The candidate vaccine was donated by IAVI, with financial support from:
- Coalition for Epidemic Preparedness Innovations (CEPI)
- Canada’s International Development Research Centre (IDRC)
- European Commission’s Health Emergency Preparedness and Response Authority (HERA)
- Africa Centres for Disease Control and Prevention (Africa CDC)
WHO co-sponsored the trial, represented at the launch by Dr. Mike Ryan, Executive Director of WHO’s Health Emergencies Programme, and Dr. Kasonde Mwinga, WHO Representative to Uganda.
Ring Vaccination Strategy to Contain the Outbreak
To rapidly assess the vaccine’s effectiveness, three vaccination rings were defined at launch. The first ring includes approximately 40 contacts and contacts of contacts of the first confirmed Ebola Sudan case—a health worker who died.
This approach follows lessons from the 2022 Ebola Sudan outbreak in Uganda, during which a randomized protocol for vaccine trials was developed. Trained teams were prepared under the leadership of the Ugandan Minister of Health, ensuring a swift trial rollout during an active outbreak.
Urgent Need for an Ebola Sudan Vaccine
Unlike the licensed vaccines available for Ebola virus (formerly known as Zaïre ebolavirus), there is currently no approved vaccine for Ebola Sudan virus. Similarly, approved treatments exist only for Ebola virus, leaving populations vulnerable to future outbreaks of Ebola Sudan.
The WHO candidate vaccine prioritization working group recommended the rVSV candidate vaccine for this trial. If proven effective, it could play a crucial role in controlling the current outbreak and provide data for vaccine licensure.
Ensuring Vaccine Readiness and Compliance
Before the trial launch, Uganda’s research teams underwent refresher training in Good Clinical Practice (GCP) and standard operating procedures for conducting emergency trials. WHO deployed experts experienced in vaccine trials and ring vaccination to support the trial’s implementation and GCP compliance.
Additionally, WHO collaborated with Ugandan authorities and IAVI to ensure the candidate vaccine doses were pre-positioned in the country and properly stored over the years. A signed agreement between WHO and IAVI will soon provide additional vaccine doses to support the trial’s expansion.
Strengthening Global Health Security
This groundbreaking trial highlights the importance of global partnerships, advance preparedness, and rapid response mechanisms in fighting high-risk infectious diseases. With Uganda at the forefront, the trial could pave the way for an approved Ebola Sudan vaccine, strengthening global outbreak response and future pandemic readiness.
The next steps will involve close monitoring of vaccine effectiveness, safety data collection, and potential expansion of trial participants. If successful, this vaccine could become a lifesaving tool in combating future Ebola Sudan outbreaks worldwide.