On Apr. 16, 2025, The Sabin Vaccine Institute announces the launch of a multi-site Phase 2 clinical trial in the U.S. for its Marburg vaccine candidate, administering doses to the first participants in Melbourne, Florida. This trial builds on ongoing Phase 2 testing in Kenya and Uganda, with initial findings from that research expected in the coming months. 

Sabin’s vaccine development efforts, including clinical trials, are becoming increasingly critical as Marburg outbreaks grow in frequency, underscoring the urgent need for vaccines to protect those at highest risk. Sabin supported an open-label Phase 2 clinical trial sponsored by the Rwanda Biomedical Centre (RBC) by supplying the investigational vaccine during Rwanda’s 2024 Marburg outbreak. More than 1,700 individuals — primarily frontline health care workers — were vaccinated, with first doses arriving within nine days of the outbreak being declared. Data from the RBC trial will be shared with Sabin to support the vaccine’s licensure.  

Rwanda’s outbreak ended on December 20 with a case fatality rate of 23%, lower than the historical average of 50%. Fatality rates in outbreaks can vary due to multiple factors, including greater surveillance, prompt detection, supportive care, and the overall response effort. On January 20, Tanzania declared an outbreak of Marburg virus disease, which ended on March 13. Currently, there are no approved vaccines for Marburg virus disease. 

For the U.S. clinical trial that has begun, Sabin will recruit 200 volunteers aged 18 to 70 across four locations – in addition to Melbourne, the vaccine will be tested at sites in Dallas, Texas; Huntsville, Alabama; and Peoria, Illinois. The randomized, placebo-controlled, double-blind trial will continue to evaluate safety and immunogenicity, and monitor vaccinated volunteers for a year.

Based on the cAd3 platform, Sabin’s single-dose investigational Marburg 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.