Chikungunya vaccine induces robust immune response in adolescents, adults

The use of chikungunya virus-like particle vaccine (CHIKV VLP) results in significantly higher seroresponse rate* and superior immunogenicity in adolescents and adults compared with placebo, according to two pivotal phase III trials presented at IDWeek 2023.

The EBSI-CV-317-004 and -005 phase III studies enrolled 3,258 healthy adolescents and adults aged 12 to <65 years (adolescent/adult cohort) and 413 healthy adults aged ≥65 years (older adult cohort), respectively, to assess the safety and immunogenicity of CHIKV VLP. [IDWeek 2023, abstract 28888]

Participants were randomized to receive either a single intramuscular injection of CHIKV VLP (adolescent/adult cohort: n=2,794; older adult cohort: n=206) or placebo (adolescent/adult cohort: n=464; older adult cohort: n=207) for 6 months.

At day 22, a higher seroresponse rate was observed with CHIKV VLP compared with placebo in the adolescent/adult cohort (98 percent vs 1 percent; p<0.0001) and older adult cohort (87.3 percent vs 1.1 percent).

CHIKV VLP also showed superior immunogenicity, as measured by geometric mean titre (GMT) at day 22 (1,618.0 vs 7.9 p<0.0001 [adolescent/adult cohort] and 724 vs 8; p<0.0001 [older adult cohort]), compared to placebo.

All key secondary endpoints were achieved for both cohorts, with higher CHIKV VLP seroresponse rates at day 15 through day 183 compared with placebo.

“Taken together, the immune response to CHIKV VLP vaccine was rapid and robust, demonstrating an increase in anti-CHIKV seroresponse rate and GMT over time,” said lead author Dr Jason Richardson from Bavarian Nordic Canada, Incorporated in Toronto, Ontario, Canada.

“Overall, all primary and key secondary endpoints were met for both phase III studies in healthy participants 12 years of age and older,” Richardson said.

Safety endpoints

Myalgia, fatigue, and headache were the most commonly reported adverse events (AEs) in both studies.

“CHIKV VLP was well-tolerated; there were no treatment-related serious AEs as determined by sponsor, and most solicited and unsolicited AEs were mild or moderate in intensity,” said Richardson.

Chikungunya is a mosquito-borne viral disease caused by the CHIKV, a Togaviridae virus. While the mortality rate is very low with CHIKV infection, morbidity is high with debilitating long-term symptoms.

“CHIKV VLP is the only VLP-based vaccine in clinical development for active immunization against chikungunya, … and these findings support the potential of this vaccine to help protect individuals 12 years and older,” the researchers noted.