Valneva SE , a specialty vaccine company, announced positive six-month antibody persistence and safety data for its Phase 2 clinical trial evaluating the safety and immunogenicity of two different dose levels of its single-shot chikungunya vaccine, IXCHIQ^®, in 304 children. Partially funded by the Coalition for Epidemic Preparedness Innovations (CEPI), with support from the European Union, the trial is intended to support a pivotal Phase 3 study in children, which the Company expects to initiate in the first quarter of 2026, with the objective of extending the product label to this age group.

Trial VLA1553-221’s six-month results were in line with the initial data the Company reported for this trial in January 2025¹. A full dose (licensed IXCHIQ^® formulation and presentation) elicited a more robust immune response in children aged one to eleven years at Day 15 and Day 180 post vaccination compared to a half dose. Overall, the immunological response profile was in line with what was previously observed in adults and adolescents²³⁴⁵⁶⁷.

The strong immune response was confirmed in CHIKV-naïve children with a 96.5% seroresponse rate (full dose) at Day 180. VLA1553 was well tolerated in children aged one to eleven years regardless of the dose or previous CHIKV infection. No safety concerns were identified.

The comparability of the VLA1553 doses tested in terms of safety and tolerability, along with the more pronounced immune response of the full dose observed for all age groups tested in children up to Day 180 post-vaccination, support the selection of the full dose for use in this population.

Juan Carlos Jaramillo M.D., Chief Medical Officer of Valneva, said, “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. Considering the significant risk chikungunya poses to individuals living in or traveling to endemic areas, it's crucial to ensure that the vaccine is accessible to people of all ages and capable of potentially offering long-term protection from a single shot. This is especially important in Low- and Middle-Income countries (LMICs) where access to vaccines is often limited.”

Brazil has reported the highest number of chikungunya cases worldwide, with over one million cases between January 2019 and July 2024⁸, followed by India with 370,000 cases during the same period. This number is rapidly increasing due to the current outbreak in the Indian states of Maharashtra and Telangana, for which the U.S. Centers for Disease Control and Prevention (CDC) issued a travel notice after identifying higher-than-expected numbers of chikungunya cases in returning travelers⁹. Additionally, two outbreaks are ongoing on the French islands of La Reunion and Mayotte¹⁰