A Phase 2 Clinical Study of VLA1553 in Healthy Children Aged 1 to 11 Years

Study Overview
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Brief Summary
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This is a multicenter, prospective, randomized, observer-blinded, three arm, phase 2 clinical study evaluating the full dose formulation of VLA1553, half dose formulation of VLA1553 and control. At least 300 male and female healthy children aged 1 to 11 years will be enrolled and the overall distribution of participants will be 2:2:1 to the two VLA1553 dose groups (n=120 each) or control (n=60).

Detailed Description
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This is a multicenter, prospective, randomized, observer-blinded, three arm, phase 2 clinical study evaluating the full dose formulation of VLA1553, half dose formulation of VLA1553 and control (Nimenrix, a tetravalent meningococcal vaccine - Men ACWY). At least 300 male and female healthy children aged 1 to 11 years will be enrolled and the overall distribution of participants will be 2:2:1 to the two VLA1553 dose groups (n=120 each) or control (Nimenrix) (n=60). As a safety precaution measure, the first 30 sentinel participants will be enrolled into the study in an open-label fashion according to an age step down scheme. After sentinel analysis, participants will be enrolled in a blinded, randomized manner into three Study Arms. Within each treatment arm participants will be stratified into three age strata: Stratum A: 7 to 11 years -children from their 7th birthday until the day before their 12th birthday. Stratum B: 3 to 6 years - children from their 3rd birthday until the day before their 7th birthday. Stratum C: 1 to 2 years - children from their 1st birthday until the day before their 3rd birthday. Age strata for the VLA1553 treatment arms are targeted to be equal in size, i.e., approximately 40 per age stratum.

Official Title
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A Randomized, Observer-blinded, Dose Response Phase 2 Study to Assess the Safety and Immunogenicity of Two Different Dose Levels of a Live-attenuated Chikungunya Virus Vaccine Candidate (VLA1553) in Healthy Children Aged 1 to 11 Years

Conditions
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Chikungunya Virus Infection

Intervention / Treatment
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* Biological: VLA1553 full dose
* Biological: VLA1553 half dose
* Biological: Control


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or female healthy children aged 7 to 11 years for Stratum A, 3 to 6 years for Stratum B and 1 to 2 years for Stratum C at the time of vaccination; Written informed consent by the participant's parent(s)/Legally Acceptable Representative(s) ((LAR(s)), according to local requirements, and written informed assent of the participant, if applicable; Exclusion Criteria: Participant who is IgM+/IgG- does not qualify for participation in this study. Participant is taking medication or other treatment for unresolved symptoms attributed to a previous CHIKV infection; or has participated in a clinical study involving an investigational CHIKV vaccine; Participant has an acute or recent infection (and who is not symptom-free in the week prior to the Screening Visit (Visit 0)

Ages Eligible for Study
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Minimum Age: 1 Year
Maximum Age: 11 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: VLA1553 full dose<br> | Biological: VLA1553 full dose<br>* Single intramuscular vaccination on Day 1 with VLA1553 full dose, a lyophilized live-attenuated Chikungunya vaccine candidate<br>|
| Experimental: VLA1553 half dose<br> | Biological: VLA1553 half dose<br>* Single intramuscular vaccination on Day 1 with VLA1553 half dose, a lyophilized live-attenuated Chikungunya vaccine candidate<br>|
| Active Comparator: Control<br>Single intramuscular vaccination on Day 1 with Nimenrix (Men ACWY vaccine), a conjugate vaccine indicated for the active immunization | Biological: Control<br>* Nimenrix<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of solicited injection site reactions |  | within 14 days post-vaccination | 
| Severity of solicited injection site reactions |  | within 14 days post-vaccination | 
| Frequency of systemic reactions |  | within 14 days post-vaccination | 
| Severity of systemic reactions |  | within 14 days post-vaccination | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of any adverse event (AE) |  | within 28 days post-vaccination | 
| Severity of any adverse event (AE) |  | within 28 days post-vaccination | 
| Frequency of unsolicited AE |  | until Month 6 (Day 180) and Month 12 (Day 365) post-vaccination | 
| Severity of unsolicited AE |  | until Month 6 (Day 180) and Month 12 (Day 365) post-vaccination | 
| Frequency of any serious adverse event (SAE) |  | until Month 6 (Day 180) and Month 12 (Day 365) post-vaccination | 
| Severity of any serious adverse event (SAE) |  | until Month 6 (Day 180) and Month 12 (Day 365) post-vaccination | 
| Immune response in baseline seronegative participants as measured by CHIKV-specific neutralizing antibody titers |  | on Day 1, Day 15, Day 29, Day 85, Day 180 and Month 12 post-vaccination |