Sabin Vaccine Institute launched a Phase 2 clinical trial for its vaccine against Sudan ebolavirus, with healthy volunteers receiving the single-dose vaccine at Makerere University Walter Reed Project (MUWRP) in Uganda. There are currently no approved vaccines for this strain of ebolavirus, which saw an outbreak end just last year. Ebolavirus disease kills on average half the people infected, according to the World Health Organization.

Sudan ebolavirus is a filovirus, in the same family as Marburg virus disease and Zaire ebolavirus, which killed 11,325 in one outbreak in West Africa from 2014-16. Ebolavirus disease spreads between people via direct contact with the blood or other bodily fluids of infected people and is highly virulent, causing hemorrhagic fever.

Based on the same cAd3 platform as its Marburg vaccine candidate, Sabin’s single-dose investigational Sudan ebolavirus vaccine was found to be promising in Phase 1 clinical and non-clinical studies, with results showing it to be safe, while eliciting rapid and robust immune responses that lasted up to 12 months.

This is Sabin’s second Phase 2 clinical trial partnership with MUWRP, based in Uganda’s capital, Kampala. A Phase 2 trial for a Marburg vaccine is already underway, having recently completed enrollment. Initial results from the Marburg trial are expected later this year.

Dr. Betty Mwesigwa, deputy executive director of MUWRP, is once again the principal investigator (PI) for the Sabin-sponsored trial for the Sudan ebolavirus vaccine. In the coming weeks, participants will also be enrolled at the Kenya Medical Research Institute in Siaya, Kenya, with Dr. Videlis Nduba serving as PI for that site. In all, 125 volunteers will participate in the trial across the two countries.

“We are delighted to advance a vaccine candidate that can thwart a deadly and devastating disease, especially one that caused a fairly recent outbreak and for which no approved treatments exist,” says Amy Finan, Sabin’s Chief Executive Officer. “Sabin’s vaccine candidate is backed by strong safety and immunogenicity data, and we hope this trial will yield further evidence to move the vaccine closer to licensure.”

The most recent outbreak of Sudan ebolavirus occurred in the fall of 2022 in Uganda, after six suspicious deaths in the Mubende district. That outbreak ultimately resulted in 55 deaths. Sabin’s vaccine was the first to arrive in Uganda during that outbreak after the World Health Organization included it as one of three vaccines for possible use in an outbreak trial. The outbreak ended on January 11, prior to vaccine being deployed for use.

“Makerere University Walter Reed Project is pleased to partner with the Sabin Vaccine Institute once again,” says Dr. Mwesigwa. “Uganda has the most experience with Sudan ebolavirus outbreaks so we understand the importance of testing and researching an effective Sudan ebolavirus vaccine that could be used in the event of an outbreak.”

The Phase 2 clinical trial will evaluate safety and immunogenicity for the vaccine among a larger group of individuals than in previous trials. This is a randomized, placebo-controlled, double-blind study, meaning that neither the participants nor the researchers will know whether trial participants receive a vaccine dose or a placebo dose until after the trial is over, an approach used to help reduce experimental bias.

Participants in the clinical trial will be monitored for a full year and will include both younger (18-50 years) and older age groups (51-70 years). Interim results are expected next year. In addition to the current trial in Uganda and Kenya, Sabin plans to conduct a similar Phase 2 clinical trial for Sudan ebolavirus vaccine in the U.S.

The Sudan ebolavirus vaccine trials are supported by the Biomedical Advanced Research and Development Authority (BARDA), part of the Administration for Strategic Preparedness and Response within the U.S. Department of Health and Human Services, under multi-year contracts between the organizations.

To date, Sabin has received around $216 million in contract awards from BARDA for furthering vaccine research and development against Sudan ebolavirus and Marburg virus diseases. BARDA and Sabin began working together in September 2019 to develop the two monovalent vaccine candidates.

This project has been supported in whole or in part with federal funds from the Department of Health and Human Services; Administration for Strategic Preparedness and Response; Biomedical Advanced Research and Development Authority (BARDA), under contract numbers 75A50119C00055 and 75A50123C00010.