Emergent BioSolutions Inc. announced results from a Phase 2 study evaluating the safety and immunogenicity of the company's adjuvanted single dose chikungunya virus virus-like particle (CHIKV VLP) vaccine candidate in prior recipients of other investigational alphavirus vaccines. The study demonstrated that the CHIKV VLP vaccine candidate was well-tolerated and immunogenic in both alphavirus vaccine-naïve participants and participants previously vaccinated against the Venezuelan equine encephalitis virus. The findings were presented at the American Society of Tropical Medicine and Hygiene (ASTMH) annual meeting.

This Phase 2 parallel group, age- and gender-matched, open-label study evaluating the safety and immunogenicity of an adjuvanted CHIKV VLP vaccine candidate in prior recipients of experimental alphavirus vaccines, in comparison to a cohort of alphavirus vaccine-naïve individuals, enrolled 60 healthy adults at two U.S. sites. The vaccine candidate was well-tolerated with no notable difference in the incidence of adverse events between the groups. The majority of solicited adverse events were mild or moderate.

The most common adverse event was local injection site pain. The seroconversion rate 21 days post-vaccination was 100% in both groups. A higher percentage of prior alphavirus vaccine candidate recipients had a four-fold rise on study day 8 than the alphavirus vaccine-naïve group.

The ASTMH annual meeting is being held in Seattle from October 30 to November 3, 2022. In addition to the oral presentation on the chikungunya vaccine candidate, Emergent has poster presentations on its smallpox vaccine, cholera vaccine, and Lassa fever vaccine candidate.