Bavarian Nordic’s Phase III study of virus-like particle (VLP)-based chikungunya virus (CHIKV) vaccine candidate CHIKV VLP (PXVX0317) in older adults has met its primary endpoints.

The placebo-controlled, randomised, double-blind study assessed the immunogenicity and safety of the vaccine in 413 healthy adults aged above 65 years.

They were randomised into a 1:1 ratio and given either a single intramuscular injection of CHIKV VLP or placebo.

On day 22 after vaccination, a strong induction of CHIKV neutralising antibodies as a marker of seroprotection was observed in 87% of vaccinees thereby meeting the primary endpoints of the study.

Majority of the subjects showed seroprotective neutralising antibodies on day 15 after the single vaccination indicating a fast onset of protection.

The vaccine was found to be well-tolerated with similar rates of adverse events observed between the placebo and the active group.

A six-month follow-up is planned to evaluate both safety and immunogenicity of CHIKV VLP.

Bavarian Nordic president and CEO Paul Chaplin said: “We are pleased to report the first Phase III results for our CHIKV vaccine candidate that clearly show this vaccine is well tolerated and highly immunogenic in an older adult population.

“They also match what has previously been reported for younger adults in an earlier Phase II study, including a fast onset of protection.

“While we still await the results from the second and larger Phase III study in adolescents and adults later this year, these highly encouraging results provide a high degree of confidence for our CHIKV vaccine programme.”

Second Phase III study intends to enrol healthy adolescents and adults aged 12 to 64 years to assess the safety and immunogenicity of the vaccine candidate.