Valneva SE (Nasdaq: VALN; Euronext Paris: VLA), a specialty vaccine company, announced additional positive Phase 3 results in adolescents for its single-dose chikungunya virus (CHIKV) vaccine, IXCHIQ ^® , demonstrating a seroresponse rate of 98.3% one year after a single vaccination. These results support and confirm the previously published pivotal Phase 3 data in adolescents (ages 12 to 17) on which Valneva has relied to submit applications for expansion of the indication to this age group in the United States ¹ , Europe and Canada ² . The results obtained from this trial are also expected to allow the vaccine to be approved in Brazil, which would be the first marketing authorization for use in an endemic population.

The one-year results of study VLA1553-321 demonstrated that vaccination with a single dose of the vaccine induced, in a subset of initially chikungunya virus-negative participants, a robust and durable immune response with a seroresponse rate of 98.3% (232 of 236 participants) one year after vaccination (day 360 ⁾ compared to a rate of 99.1% (232 of 234 participants) six months after vaccination (day 180 ⁾ and a rate of 98.8% (248 of 251 participants) 28 days ^3 , 4 after vaccination. These results also complement the long-term persistence data previously reported for adults, confirming a strong and durable immune response.

Geometric mean antibody titers (GMTs) consistently exceeded the seroresponse threshold defined with the U.S. Food and Drug Administration (FDA) to serve as an indicator of protection in initially negative participants who received a single dose of the vaccine.

Furthermore, data obtained one year after vaccination confirmed that a single dose of the vaccine was generally safe and well tolerated in adolescents who received it. An independent Data Safety Monitoring Board (DSMB) continuously assessed the safety of the trial and identified no concerns.