Equine encephalitis



Under a contract with the U.S. Government, awarded in 2018, Bavarian Nordic has developed MVA-BN WEV, a vaccine against equine encephalitis virus, an emerging mosquito-borne virus which can result in the rare condition of encephalitis and death.

In June 2020, topline results from the first-in-human trial of MVA-BN WEV were reported. The study enrolled 45 healthy adults in three treatment groups receiving different doses of the vaccine. All subjects were revaccinated after four weeks.

Data from the study showed that the vaccine was well tolerated and immunogenic across all dose groups. Neutralizing antibody responses were observed in all dose groups, with peak levels reached after the second vaccination. Responses were detected as early as 2 weeks after the first vaccination in the highest dose group, in which 100% seroconversion was observed for all subjects after the second vaccination. The most common vaccine-related adverse event was injection site pain. These clinically meaningful Phase 1 data warrant further clinical investigation, and Bavarian Nordic is seeking additional funding for the further clinical advancement of the vaccine candidate. 

Western, Eastern and Venezuelan equine encephalitis viruses vary in infection rates and severity of disease, although all three pathogens are associated with risks of flu-like symptoms, potential central nervous disorders, and death. The virus is spread by mosquitos to humans and can result in the rare condition of encephalitis in about 5% of the people that become infected. In the United States, an increase in cases of Eastern equine encephalitis, known also as Triple E, has been reported over the past years, and in 2019 almost 40 cases, including 15 deaths were reported by the CDC in what is the largest ever recorded outbreak of Triple E. There are currently no approved vaccines against any of the equine encephalitis viruses.