Emergent BioSolutions Inc. announced the first participant dosed in its pivotal phase 3 study evaluating the safety and immunogenicity of the company’s investigational chikungunya virus (CHIKV) virus-like particle (VLP) vaccine candidate, CHIKV VLP, in a single dose. CHIKV VLP is the only VLP-based vaccine currently in clinical development for active immunization against chikungunya disease. The goal of this multi-center, randomized, double blind, placebo-controlled study is to evaluate the safety and immunogenicity of the CHIKV VLP vaccine candidate in healthy individuals aged 12 to 64 as well as to demonstrate the consistency of the chikungunya virus (CHIKV) serum neutralizing antibody (SNA) response across three manufactured vaccine candidate lots. The study will observe the CHIKV SNA response at day 22 as measured by geometric mean titer and seroresponse rate and will enroll at least 3,150 participants in up to 49 U.S. sites. The structure of the CHIKV VLP is nearly identical to the wild-type virus but does not pose a risk of replication. Studies have shown that in general, other VLP vaccines are highly immunogenic, safe, and typically elicit high titer neutralizing antibodies, which are needed to protect against chikungunya virus.i,ii There is currently no licensed vaccine, VLP or otherwise, to prevent chikungunya virus disease.