Valneva's Chikungunya Vaccine IXCHIQ® Shows Positive 12-Month Phase 2 Results in Children

Positive Final Phase 2 Data for IXCHIQ® in Pediatric Population

Valneva SE, a specialty vaccine company based in France, has announced positive final Phase 2 antibody persistence and safety results for its single-shot Chikungunya vaccine, IXCHIQ®, in children. The announcement, made on December 10, 2025, details the outcomes of the VLA1553-221 clinical trial, which evaluated the vaccine in 304 children aged one to eleven years.

The trial demonstrated that IXCHIQ® was well tolerated across all participants, regardless of the dose received or any prior Chikungunya infection. No safety concerns were identified during the 12-month observation period. Antibody levels remained high for a full year post-vaccination in both dose groups tested, with the full dose eliciting a more robust immune response compared to a half dose. Specifically, a 94.7% seroresponse rate was observed in Chikungunya-naïve children who received the full dose at Day 360.

Trial Details and Future Development

The immunological response profile observed in children was consistent with previous findings in adult and adolescent populations. These positive results are crucial as they support the selection of the full dose for a future Phase 3 trial in children. Valneva plans to initiate this pivotal Phase 3 development after gathering additional real-world experience from the adolescent population.

The Phase 2 trial received partial funding from the Coalition for Epidemic Preparedness Innovations (CEPI), with additional support from the European Union. This collaborative effort underscores the global commitment to addressing the unmet medical need for a Chikungunya vaccine, particularly for vulnerable pediatric groups.

Addressing an Unmet Medical Need

Chikungunya is a mosquito-borne viral disease characterized by symptoms such as fever, severe joint and muscle pain, headache, nausea, fatigue, and rash. While rarely fatal, the disease can cause debilitating symptoms that significantly impact a patient's quality of life, with joint pain sometimes persisting for months or even years. Currently, there is no specific antiviral treatment for Chikungunya, and existing treatments are primarily symptomatic.

IXCHIQ® is already approved for individuals 18 years of age and older in the United States, Canada, Europe, and Brazil. The successful pediatric Phase 2 results mark a significant step towards potentially extending the vaccine's availability to younger populations, offering a preventative measure against this impactful disease.