Uganda's 2025 SVD Outbreak: How Africa's Best Ebola Responder Contained a Virus With No Vaccine
Uganda declared its sixth Sudan virus disease outbreak over on 26 April 2025 — 86 days after it began. Here's a detailed account of how the country contained a deadly virus for which no approved vaccine or treatment exists, and what the world learned.
Six Outbreaks, Six Containments
When Uganda declared a Sudan virus disease (SVD) outbreak on 30 January 2025, the country was confronting a disease it had faced — and defeated — five times before. Since 2000, Uganda has experienced more Ebola-family outbreaks than any other nation outside the DRC, yet it has never allowed a single outbreak to spiral into a regional epidemic.
On 26 April 2025, after 42 consecutive days without a new case, Uganda’s Ministry of Health declared the sixth outbreak over. Total toll: 14 cases (12 confirmed, 2 probable) and 4 deaths, for a case fatality rate of 29% — far below the historical SVD average of 41%.
This is the story of how that was achieved.
Timeline of the 2025 SVD Outbreak
| Date | Event |
|---|---|
| 30 January 2025 | Outbreak declared. Index case: a healthcare worker at Bwera hospital, Ntoroko district |
| 3 February 2025 | TOKOMEZA SVD vaccine trial launched (Day 4 post-declaration) |
| 15 February 2025 | Outbreak spreads to Kampala; contact tracing scales to urban environment |
| 8 March 2025 | 12th confirmed case identified; last confirmed transmission event |
| 26 April 2025 | Outbreak declared over (42 days since last case) |
Affected Districts
Seven districts across Uganda were affected, reflecting SVD’s pattern of following transport corridors and family contacts rather than geographic clustering:
- Ntoroko (index case, border with DRC)
- Fort Portal City (second cluster, major regional hub)
- Jinja (third cluster, eastern Uganda)
- Kampala (urban cases, contact of Fort Portal cluster)
- Kyegegwa, Mbale, Wakiso (individual cases, contact tracing)
Why SVD Is Particularly Dangerous to Contain
Sudan ebolavirus (SUDV) presents different challenges than Zaire ebolavirus, which is better understood and for which approved countermeasures exist:
No approved vaccine. The rVSV-ZEBOV (Ervebo) vaccine, the cornerstone of modern Ebola response, is entirely Zaire-specific. As of January 2025, no SVD vaccine had completed Phase 3 efficacy trials.
No approved treatment. Monoclonal antibodies Inmazeb and Ebanga — approved for Zaire-strain EVD — have no efficacy data for Sudan virus disease. Remdesivir and other antivirals have been used compassionately without clear benefit.
Clinical similarity to other febrile illnesses. Early SVD presents with fever, fatigue, and body aches indistinguishable from malaria, typhoid, or other endemic diseases. In resource-constrained settings, this creates diagnostic delay and infection risk for healthcare workers.
Uganda’s 2022 SVD outbreak — the largest in 18 years — killed 55 of 164 infected people, including 8 healthcare workers, and required 140 days to contain. The 2025 outbreak was contained in 86 days with 10 fewer deaths.
The TOKOMEZA SVD Trial: A Milestone in Vaccine Research
The most significant development of the 2025 outbreak was the launch of the TOKOMEZA SVD vaccine efficacy trial just 4 days after outbreak declaration — an unprecedented speed for a clinical trial in an outbreak setting.
TOKOMEZA (the name means “contain” in Swahili) tested the ChAd3-SUDV candidate vaccine developed by Oxford University and the Jenner Institute, which had shown strong immunogenicity in Phase 1/2 trials. The trial enrolled:
- High-risk contacts of confirmed SVD cases
- Healthcare workers in affected facilities
- Using a ring vaccination design — the same trial design used for VSV-ZEBOV during the 2015 Guinea trials that proved its efficacy
The trial was conducted by a consortium including Uganda’s Ministry of Health, UVRI, WHO, and international academic partners, with WHO’s R&D Blueprint providing regulatory fast-track support.
Why This Matters
Before 2025, the global response to SVD outbreaks had a significant gap: while Zaire responses could rely on Ervebo for ring vaccination of contacts, SVD responses had no equivalent tool. Healthcare workers and family contacts could only be protected by strict barrier nursing and isolation — measures that are effective but strain health systems and create treatment delays.
The TOKOMEZA trial generated preliminary immunogenicity data during the outbreak. While full efficacy results require a larger outbreak to achieve statistical power, the trial established that an SVD vaccine candidate can be safely and rapidly deployed in an active outbreak — critical proof-of-concept for future events. Full trial results are expected in late 2025/early 2026.
What Made the Containment Successful?
Public health analysts attributed Uganda’s rapid containment to several reinforcing factors:
1. Institutional Memory
Uganda’s response teams include personnel with direct experience from the 2022 outbreak — and in some cases from earlier events. Established response protocols, pre-positioned PPE stockpiles, and known community engagement networks meant that response speed was not slowed by institutional learning.
2. Rapid Laboratory Confirmation
The Uganda Virus Research Institute (UVRI) confirmed the index case within 72 hours of sample collection using RT-PCR. Early confirmation prevented further healthcare worker exposure and triggered immediate contact tracing before the cluster expanded.
3. Urban Contact Tracing at Scale
When cases reached Kampala — a city of over 3 million — response teams deployed a rapid urban contact tracing protocol. In contrast to 2022, digital contact tracing tools supported faster identification of potentially exposed individuals in the dense urban environment.
4. Community Trust
Community trust in the response, carefully built after the 2022 outbreak, meant that self-isolation compliance was high and community informants proactively reported suspected cases rather than concealing them.
5. International Support, Locally Led
WHO deployed 67 technical experts and released US$3.4 million from its Contingency Fund for Emergencies within the first two weeks. Critically, the international support was provided within Uganda’s national command structure rather than replacing it — a model refined after the contested DRC 2018–2020 response.
CFR of 29%: What Drove Better Survival?
The 2025 outbreak’s 29% CFR compares favourably with historic SVD events (average ~41%) and with Uganda’s own 2022 outbreak (34%). Several factors likely contributed:
- Earlier presentation: Increased community awareness meant more patients sought care before advanced haemorrhagic disease onset
- Aggressive supportive care: The ETU at Fort Portal applied intensive fluid management and electrolyte correction, learned from treatment advances in the 2022 outbreak
- No large healthcare worker cluster: Unlike 2022, where healthcare worker infections created amplification clusters, 2025 saw zero healthcare worker infections after the index case — reflecting better PPE compliance
Lessons for the Global Health System
Uganda’s 2025 experience offers three transferable lessons:
1. Outbreak readiness infrastructure compounds. Each containment makes the next containment faster. Uganda’s declining outbreak duration across its six SVD events — from 224 days (2000) to 86 days (2025) — demonstrates that sustained investment in outbreak response capability creates a measurable, compounding return.
2. Rapid vaccine trials are operationally feasible. TOKOMEZA proved that a clinical trial can be designed, IRB-approved, and initiated within 4 days of outbreak declaration. This sets a new standard for the speed at which evidence generation can proceed during outbreaks.
3. The SVD vaccine gap remains unresolved. Despite TOKOMEZA, no SVD vaccine has yet been approved or stockpiled. Given Uganda’s subsequent June 2026 vulnerability to the Bundibugyo cross-border outbreak — a separate species, also without approved countermeasures — the broader lesson is clear: the world needs pan-filovirus countermeasure investment, not species-by-species reactive development.
The 2025 SVD outbreak is now a historical event. As of May 2026, Uganda is managing a separate active Bundibugyo ebolavirus outbreak. See our 2026 Bundibugyo outbreak update for the latest situation.
Sources: Uganda Ministry of Health Outbreak Reports (2025), WHO Disease Outbreak News item 2025-DON566, Africa CDC Situation Reports, Journal of Infectious Diseases SVD trial preliminary data briefing.