A Sudan Ebola vaccine, provided by the International AIDS Vaccine Initiative (IAVI), is being investigated in a Uganda vaccine trial that was launched just four days after the country declared an outbreak.
The vaccine is being investigated as part of a ring trial led by the World Health Organization (WHO) at Makerere University Lung Institute in the Ugandan capital, Kampala. Evaluation of the recombinant vesicular stomatitis virus (rVSV) vaccine has been prioritised as part of a global collaborative effort supporting the country’s Ebolavirus outbreak.
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Principal investigators from Makerere University and the Uganda Virus Research Institute (UVRI), with support from WHO and other partners, including Uganda’s Ministry of Health, prepared the randomised trial to begin the first dosing just four days after the outbreak was confirmed on 30 January.
Dosing began at the Mulago Referral Hospital in the capital yesterday (3 February) after three vaccination rings were defined. The first ring involves approximately 40 contacts from the first reported and confirmed case, a health worker who died on 29 January. The efficacy of ring trials was established in a study published in the New England Journal of Medicine, which evaluated trials of MSD’s rVSV vaccine Ervebo that was investigated in the Zaire Ebola outbreak in the Democratic Republic of Congo.
IAVI president Dr Mark Feinberg said: “We believe this clinical trial represents an important step toward evaluating the potential of IAVI’s vaccine to protect exposed individuals from Ebola Sudan infection, as well as demonstrating its value as a safe, effective, and accessible new tool to include in comprehensive outbreak responses in the future.
“Critically, having vaccine doses readily available in the country made it possible for us all to mobilise in just days and to be able to incorporate the evaluation of a promising Ebola Sudan vaccine clinical trial into the public health response very soon after the first reports of the current outbreak.”
This will be the first trial to assess the clinical efficacy of a vaccine against Ebola disease due to the Sudan virus. In 2023, IAVI initiated a Phase I trial (NCT05724472) which determined the rVSV Ebola Sudan vaccine was well tolerated with immune responses detected in all groups. This data was shared in November 2024 during the annual meeting American Society of Tropical Medicine and Hygiene.
IAVI is also investigating the rVSV platform technology elsewhere in its portfolio, including a Lassa virus vaccine candidate currently in Phase II trials in West Africa.
Uganda’s preparedness key in speedy trial set-up
Evaluation of IAVI’s Ebola Sudan vaccine was already prepositioned in the country, however, the recent outbreak has seen the WHO sign an agreement for IAVI to provide more doses of the shot.
The most recent Ebola outbreak is the sixth the country has faced, the last being in 2022. The virus causes severe haemorrhagic fever disease and holds a fatality rate of between 41% and 70%. Although several promising candidate medical countermeasures are progressing through clinical development, there are no vaccines or therapeutics approved for Ebola Sudan. Ebola Zaire vaccines are not effective in protecting against Ebola Sudan.
During the 2022 outbreak, a randomised protocol for candidate vaccines was developed with teams trained in good clinical practice (GCP) and standard operating procedures of how to run studies during a national outbreak. Staff completed refresher training in recent days. WHO colleagues experienced in trials and ring vaccination arrived in Uganda over the weekend to support the trial implementation and GCP compliance.
According to GlobalData’s Pharmaceutical Intelligence Centre, there are 16 Ebola drugs in active clinical development, ten in Phase I, two in Phase II, and four in Phase III. Just one of the Phase III candidates, a combination of Johnson and Johnson’s Mvabea and Zabdeno, is being investigated in Ebola Sudan. The Mvebea and Zabdeno regiment is approved for the Zaire ebolavirus.
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