Denmark-based Bavarian Nordic has reported positive immunogenicity results from the Phase III trial of its virus-like particle (VLP)-based chikungunya virus (CHIKV) vaccine (CHIKV VLP) in healthy adults aged 65 years or older.

CHIKV VLP (PXVX0317) is an adjuvant vaccine for active immunisation against chikungunya.

Chikungunya is a viral disease caused by CHIKV and transmitted by Aedes mosquitoes. It is prevalent in Africa, Asia, and America, according to the World Health Organisation (WHO).

Bavarian Nordic CEO Paul Chaplin reported that the Phase III positive results inspired "a high degree of confidence" regarding the company’s CHIKV vaccine program.

Results from the randomised, placebo-controlled Phase III trial (NCT05349617) demonstrated seroprotective neutralising antibodies in 82% of the subjects 15 days after receiving a single administration.

Another chikungunya vaccine candidate currently undergoing Phase III trials is Valneva, which recently published the Phase III data for its live-attenuated vaccine ahead of its FDA Prescription Drug User Fee Act (PDUFA) date at the end of August 2023.

CHIKV VLP’s Phase III data

Four hundred and thirteen healthy participants were enrolled in the study and randomised 1:1 for either a single intramuscular injection of CHIKV VLP or a placebo.

The study met its primary endpoints by inducing an immunogenic response in CHIKV-neutralising antibodies in healthy adults aged 65 years or older, 22 days post-vaccination. Additionally, 87% of the participants’ neutralising antibody titers exceeded the seroprotection threshold.

CHIKV VLP was well-tolerated, with similar rates of adverse events observed in the vaccine and placebo groups.

The trial will continue with a six-month follow-up to evaluate CHIKV VLP’s safety and immunogenicity.

Bavarian is expected to have a result readout for the randomised, placebo-controlled Phase III study (NCT05072080) of the CHIKV vaccine in healthy adolescents and adults (aged 12 to 64 years) during the third quarter of 2023.