Valneva SE reported positive antibody persistence data twelve months after vaccination with a single dose of its chikungunya vaccine candidate, VLA1553. Following positive immunogenicity and safety data for Phase 3 study VLA1553-301 in March 20221, Valneva set up a dedicated antibody persistence trial (VLA1553-303) to monitor a subset of participants for a period of at least five years and confirm the anticipated long-term durability of the antibody response after a single vaccination. The antibody persistence trial enrolled 363 healthy adult participants and followed them from month 6 after vaccination to month 12.99% of participants retained neutralizing antibody titers above the seroresponse threshold of 150 12 months after the single-dose vaccination.

These antibody levels confirm the antibody persistence profile observed in an earlier study. The antibody persistence was similar in older adults aged =65 years, who retained neutralizing antibody titers comparable to younger adults throughout the follow-up. These results follow completion of the pivotal study VLA1553-301, for which a seroresponse rate of 96% six months after vaccination was reported.

The study will continue to monitor antibody persistence on an annual basis. No safety concerns were identified for the duration of the follow-up study, confirming the safety profile observed in previous studies. Valneva expects to finalize its BLA submission with the FDA by the end of 2022.

Once completed, and if the FDA accepts the filing, the FDA will determine priority review eligibility along with the action due date upon which it will complete its evaluation. The program received FDA Fast Track and Breakthrough Therapy designations in 2018 and 2021, respectively. VLA1553 was also granted PRIority MEdicine (PRIME) designation by the EMA in 2020.

Valneva currently plans to make additional regulatory submissions for VLA1553 in 2023. Valneva also initiated a Phase 3 trial in adolescents conducted in Brazil by Instituto Butantan to support the label extension in this age group following a potential initial regulatory approval.