Valneva's Chikungunya Vaccine Shows Promising Long-Term Immune Response in Adolescents

Valneva SE (Nasdaq: VALN; Euronext Paris: VLA), a specialty vaccine company, has reported encouraging data from its Phase 3 study, VLA1553-321, demonstrating a sustained 98.3% seroresponse rate one year after a single vaccination with its chikungunya vaccine, IXCHIQ®, in adolescents aged 12 to 17 years. This high and long-lasting immune response is a positive indicator of the vaccine's potential efficacy in preventing chikungunya disease in this age group.

The one-year data showed that a single-dose vaccination induced a high, sustained immune response in an immunogenicity subset of participants who were CHIKV negative at baseline. The seroresponse rate of 98.3% (232 out of 236 participants) at Day 360 was consistent with the rates observed at Day 180 (99.1%) and Day 29 (98.8%). Geometric mean antibody titers (GMTs) consistently surpassed the seroresponse threshold defined by the U.S. Food and Drug Administration (FDA) as the surrogate of protection in baseline seronegative participants who received a single dose of the vaccine.



The vaccine was generally well-tolerated in adolescents, with no safety issues identified by the Independent Data Safety Monitoring Board (IDSMB). The majority of solicited adverse events observed following IXCHIQ® administration were mild or moderate and resolved within three days post vaccination.

Juan Carlos Jaramillo M.D., Chief Medical Officer of Valneva, commented on the results, "These additional adolescent data confirm IXCHIQ®’s ability to induce a robust, long-lasting antibody response in both younger people and adults with a single vaccination. Given the substantial risk that chikungunya presents to individuals residing in or traveling to endemic regions, it's imperative to ensure the vaccine is available to all age groups and has the potential to offer long-term protection, particularly in low- and middle-income countries (LMICs) where vaccine access is often limited. We are now looking forward to the first data in children which we expect to report imminently."

The Coalition for Epidemic Preparedness Innovations (CEPI) and the European Union's Horizon 2020 program funded the VLA1553-321 trial, which was conducted in collaboration with Instituto Butantan in Brazil. The trial represents the first clinical trial conducted in an endemic area and with individuals previously infected with CHIKV. Valneva's vaccine, IXCHIQ®, is the world's first and only licensed chikungunya vaccine available to address this significant unmet medical need.

In conclusion, Valneva's chikungunya vaccine, IXCHIQ®, has shown promising long-term immune response in adolescents, with a high and sustained seroresponse rate one year after a single vaccination. The vaccine's safety profile and potential to offer long-term protection make it an attractive option for preventing chikungunya disease in this age group. As the vaccine continues to be evaluated in children and other populations, its potential to address the growing global threat of chikungunya becomes increasingly apparent.