On February 3, 2025, Uganda’s Ministry of Health, in collaboration with global health organizations, launched the first-ever clinical efficacy trial for an experimental Ebola vaccine targeting the Sudan virus species. This marks a significant step in the fight against the Sudan virus, a strain of Ebolavirus responsible for periodic outbreaks in East and Central Africa.
Understanding Sudan Virus Disease (SVD)
Sudan virus disease (SVD) is a severe illness caused by the Sudan virus, one of the six known species of the Ebolavirus genus. It is highly contagious and can lead to high fatality rates, with past outbreaks reporting case-fatality rates ranging from 41% to 100%. Unlike Zaire Ebolavirus the strain responsible for the 2014–2016 West African Ebola outbreak the Sudan virus has no approved vaccine or specific antiviral treatment.
SVD spreads through direct contact with infected bodily fluids, contaminated surfaces, or infected animals such as fruit bats and non-human primates. Symptoms typically appear 2 to 21 days after exposure and include fever, severe weakness, muscle pain, vomiting, diarrhea, and in some cases, unexplained bleeding. Without early medical intervention, the disease can quickly become fatal.
The Experimental Vaccine Trial
The new clinical efficacy trial aims to test an experimental vaccine designed to provide immunity against the Sudan virus. The trial, supported by international health agencies and vaccine developers, is part of broader efforts to combat Ebola outbreaks in Africa. Unlike previous Ebola vaccines that have been approved for the Zaire strain, this vaccine specifically targets the Sudan virus, which has been responsible for multiple outbreaks, including one in Uganda in 2022.
Since 2014, Ebolavirus vaccine research has focused on several technologies, including:
- Replication-deficient adenovirus vectors (used in many modern vaccines)
- Replication-competent vesicular stomatitis virus (rVSV) vectors
- Human parainfluenza vectors
- Virus-like nanoparticle preparations
While the Zaire Ebolavirus vaccines have been successfully licensed by the U.S. Food and Drug Administration (FDA), the European Medicines Agency (EMA), and the World Health Organization (WHO), vaccines for the Sudan virus remain in the experimental phase. The new trial in Uganda represents a major milestone in addressing this gap.Symptoms typically appear 2 to 21 days after exposure and include fever, severe weakness, muscle pain, vomiting, diarrhea, and in some cases, unexplained bleeding. Without early medical intervention, the disease can quickly become fatal.
Global Response and Webinar for Health Experts
International health agencies continue to monitor the outbreak and support Uganda’s response efforts. So far, no suspected, probable, or confirmed Ebola cases linked to this outbreak have been reported outside Uganda, including in the United States.
To keep health professionals and researchers informed, a free webinar has been organized under the WHO’s EPI-WIN platform. Interested participants can register via Zoom to learn more about ongoing research, preparedness measures, and vaccine development.
Uganda’s latest outbreak highlights the urgent need for continued investment in Ebola research and vaccine development. While the new clinical trial brings hope, more work remains to ensure effective vaccines and treatments are available for all strains of the Ebolavirus. Global cooperation will be essential in advancing these efforts and protecting vulnerable communities from future outbreaks.
