Bavarian Nordic A/S announced positive topline results from a randomized, double-blind, placebo-controlled Phase 3 clinical trial (NCT05072080) of its virus-like particle (VLP)-based chikungunya virus vaccine candidate, CHIKV VLP (PXVX0317) in adults and adolescents aged 12 to 64 years of age. A total of 3,254 participants were enrolled and randomized to receive either a single intramuscular injection of CHIKV VLP, or placebo. The results up to day 22 post vaccination showed that CHIKV VLP was highly immunogenic in healthy adolescents and adults, as demonstrated by the strong induction of chikungunya neutralizing antibodies in 98% of vaccinees in the active group.

The strong neutralizing antibody titres were equal to, or exceeded the threshold agreed with authorities as a marker of seroprotection, meeting primary objectives of the study. Importantly, CHIKV VLP induced significant neutralizing antibodies in 97% of the subjects at 2 weeks post vaccination, confirming a rapid onset of protective levels of immunity. These responses were robust and durable, as 86% of the subjects had seroprotective levels of neutralizing antibodies 6 months post vaccination.

CHIKV VLP was well-tolerated in this adolescent and adult population and adverse events were mainly mild or moderate in nature. In June 2023, Bavarian Nordic reported positive topline data from a similar Phase 3 study in healthy adults =65 years of age (NCT05349617), which demonstrated that CHIKV VLP induced chikungunya neutralizing antibodies in 87% of vaccinees 22 days after a single vaccination and was well-tolerated. Results from both studies will form the basis for submission of a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) and a Marketing Authorization Application (MAA) to the European Medicines Agency (EMA) in 2024 to support potential launch of the vaccine in 2025.