NCT07133178

A Trial to Evaluate the Safety and Immunogenicity of VLA1553 in Healthy Children

A Multicenter, Randomized, Controlled, Double-blind Pivotal Phase 3 Trial to Evaluate the Safety and Immunogenicity of a Live-attenuated Chikungunya Virus Vaccine (VLA1553) in Healthy Children Aged 1 to 11 Years

• Status: Withdrawn
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 0 (actual)
• Sponsor: Valneva Austria GmbH · Industry
• Sex: All
• Age: 1 Year – 11 Years
• Healthy volunteers: Accepted

Summary

VLA1553-322 is a multicenter, prospective, randomized, double-blind, phase 3 clinical trial evaluating VLA1553 in comparison to a comparator (Nimenrix®) for each stratum (age group). At least 3,000 male and female healthy children aged 1 to 11 years will be enrolled and randomized 3:1 to either VLA1553 (n=2,250) or comparator (Nimenrix®) (n=750).

Detailed description

This is a multicenter, prospective, randomized, double-blind, Phase 3 clinical trial evaluating VLA1553 in comparison to a comparator (Nimenrix®) in healthy children aged 1 to 11 years after a single vaccination in endemic countries. The overall trial duration (First Participant In - Last Participant Out) is estimated to be approximately 22 months. Individual participation is approximately 13 months (immunogenicity subset) from ICF signature to trial completion, unless prematurely discontinued. At least 3,000 male and female healthy children aged 1 to 11 years will be enrolled and randomized 3:1 to either VLA1553 (n=2,250) or comparator (Nimenrix®) (n=750). These children will be screened for evidence of previous CHIKV exposure. The trial will be conducted in Latin America and / or Southeast Asia to ensure a diverse participant population and broad applicability of results. An independent Data and Safety Monitoring Board (DSMB) will oversee participant safety, review interim data, and provide recommendations on the trial's continuation. Additionally, a Valneva internal Safety Review Committee (SRC) will review safety data according to their pertinent SRC Charter. The trial is divided into three sequential parts with predefined timepoints: Part A (Day 29, Visit 4), Part B (Month 6, Visit 6) and Part C (Month 12, Visit 7). Analyses for each part will be conducted independently after the last participant completes the respective visit, with Part A analyzed after Day 29, Part B after Month 6, and Part C after Month 12.

Conditions

• Chikungunya Virus Infection

Interventions

Type	Name	Description
BIOLOGICAL	VLA1553	Single intramuscular vaccination on Day 1 with VLA1553 full dose, a lyophilized live-attenuated Chikungunya vaccine
BIOLOGICAL	Control	Single intramuscular vaccination on Day 1 with Nimenrix (Men ACWY vaccine), a conjugate vaccine indicated for the active immunization

Timeline

• Start date: 2026-02-06
• Primary completion: 2026-12-01
• Completion: 2027-11-01
• First posted: 2025-08-20
• Last updated: 2025-12-31

Regulatory

• FDA-regulated drug study