Valneva SE announced positive six-month antibody persistence and safety data from its Phase 2 clinical trial evaluating two dose levels of its single-shot chikungunya vaccine, IXCHIQ, in 304 children aged one to eleven years. The results support the company's planned Phase 3 pediatric study, expected to begin in the first quarter of 2026.
Strong Immune Response Maintained at Six Months
The trial demonstrated that a full dose of VLA1553 elicited a more robust immune response in children compared to a half dose at both Day 15 and Day 180 post-vaccination. In infection-naïve children, the full dose achieved a 96.5% seroresponse rate at Day 180, confirming sustained antibody levels six months after vaccination.
"The six months persistence and safety data in children are aligned with the robust antibody response and safety profile we reported in adolescents after a single vaccination," said Juan Carlos Jaramillo, Chief Medical Officer of Valneva.
The immunological response profile observed in children was consistent with previous results in adults and adolescents. VLA1553 was well tolerated across all age groups regardless of dose level or previous chikungunya virus (CHIKV) infection status, with no safety concerns identified.
Full Dose Selection for Phase 3 Trial
The comparability of safety and tolerability between dose levels, combined with the more pronounced immune response of the full dose across all pediatric age groups tested, supports the selection of the full dose formulation for the upcoming pivotal Phase 3 study. This trial, partially funded by the Coalition for Epidemic Preparedness Innovations (CEPI) with European Union support, aims to extend the product label to include children.
Addressing Global Disease Burden
Chikungunya virus represents a significant global health threat, transmitted by infected Aedes mosquitoes and causing fever, severe joint and muscle pain, headache, nausea, fatigue, and rash. Joint pain can be debilitating and persist for weeks to years.
Brazil has reported the highest number of chikungunya cases worldwide, with over one million cases between January 2019 and July 2024, followed by India with 370,000 cases during the same period. Between 2013 and 2023, more than 3.7 million cases were reported in the Americas alone.
Since its re-emergence in 2004, CHIKV has been identified in over 110 countries across Asia, Africa, Europe, and the Americas. The disease burden is expected to grow with climate change as mosquito vectors continue to expand geographically, prompting the World Health Organization to highlight chikungunya as a major public health problem.
Trial Design and Regulatory Context
The VLA1553-221 trial is a multi-center, randomized, observer-blinded, dose response Phase 2 study conducted at three sites in the Dominican Republic and Honduras. Participants were randomized 2:2:1 to receive either a full dose, half dose of the vaccine, or an active control (Nimenrix).
The pediatric development program comes as federal agencies have provided specific guidance on the vaccine's use. The CDC's Advisory Committee on Immunization Practices has recommended the chikungunya vaccine for travelers aged 12 and older visiting outbreak or high-risk areas, as well as for laboratory workers with potential occupational exposure.
