A single shot vaccine for mosquito-borne disease chikungunya has had positive antibody persistence data 12 months after vaccination.

The primary endpoint also met with a 99% seroresponse rate.  The disease is caused by the chikungunya virus (CHIKV), a Togaviridae virus, transmitted by Aedes mosquitoes.

Following positive immunogenicity and safety data from a phase 3 study of the vaccine, VLA1553-301, in March 2022, Valneva set up a dedicated antibody persistence trial (VLA1553-303). This was 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.

Dedicated antibody persistence

The antibody persistence trial enrolled 363 healthy adult participants and followed them from month six after vaccination to month 12. Of those participants 99% retained neutralizing antibody titers above the seroresponse threshold of 1502 up to 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 and under, 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.

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No safety concerns

Juan Carlos Jaramillo chief medical officer of Valneva, said: “We are excited about these twelve-month data which are in line with what we saw from our previous read out at month six, and strengthen the possibilities of inducing a long-lasting antibody response with our chikungunya vaccine candidate. We are looking forward to completing the BLA rolling submission to the FDA and potentially to changing people’s lives. If our investigational vaccine is approved, we are confident that it can help address this major, growing and unmet public health threat.”

Valneva expects to finalize its Biologics License Application (BLA) submission with the U.S. Food and Drug Administration (FDA) by the end of this year (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 European Medicines Agency in 2020. The company 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.