• Primary endpoint met with 97% seroresponse rate 24 months after a single vaccination
  • Antibody levels remained high and well above the seroresponse threshold, further supporting the anticipated long-term durability of the immune response
  • No safety concerns identified in long-term follow up

Saint-Herblain (France), December 4, 2023 – Valneva SE (Nasdaq: VALN; Euronext Paris: VLA), a specialty vaccine company, today reported positive antibody persistence data twenty-four months after vaccination with a single dose of its chikungunya vaccine IXCHIQ®, further supporting the anticipated long-term durability of the immune response and in line with positive twelve-month persistence data the Company reported in December 2022[1]. These persistence data are intended to supplement the existing approval by U.S. FDA and ongoing regulatory approval processes.

97% of the 316 healthy adults still enrolled in the trial retained neutralizing antibody titers above the seroresponse threshold[2] twenty-four months after the single-dose vaccination. The persistence of antibodies in older adults aged 65 and above was as robust as in younger adults, and even slightly higher in terms of geometric mean titers (GMTs) and seroconversion rates (SRRs). This outcome underscores the vaccine’s potential to offer strong and lasting protection against chikungunya across different age groups. These results follow completion of the pivotal Phase 3 study published in the Lancet[3] in which a seroresponse rate of 96% six months after a single vaccination1 was reported.

Study VLA1553-303 collected long-term safety by following any Adverse Event of Special Interest (AESI) from the preceding study and collecting new-onset SAEs. No safety concerns were identified for the duration of the 24-month follow-up and, as reported in the 12-months data analysis, no AESI was ongoing when participants were enrolled in the trial.

Juan Carlos Jaramillo M.D., Chief Medical Officer of Valneva, said, “We are very pleased about these twenty-four-month data which confirm IXCHIQ®‘s ability to induce a robust, long-lasting antibody response in both younger and older adults with a single vaccination. Being the world’s first approved vaccine against chikungunya, each positive outcome further strengthens the defense against this significant and expanding public health threat.”

Valneva was granted U.S. FDA approval[4] for its chikungunya vaccine IXCHIQ® in November 2023[5]. Two marketing applications are currently under review by EMA and Health Canada with potential approvals in mid-2024. A clinical study in adolescents is also ongoing in Brazil for which the Company reported positive pivotal Phase 3 data in November 2023[6]. This study is intended to support label extension in this age group and licensure of the vaccine in Brazil, which would be the first potential approval for use in endemic populations.

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