Antibody Persistence And Long Term Safety Of A Chikungunya Virus Vaccine Candidate (VLA1553)

Study Overview
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Brief Summary
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In this open-label Phase 3b, single arm study, persistence of antibodies and long term safety will be evaluated in up to 375 subjects rolled over from study VLA1553-301 (NCT number: NCT04546724).

Detailed Description
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In this open-label Phase 3b, single arm study, persistence of antibodies and long term safety in up to 375 subjects rolled over from study VLA1553-301 (NCT number: NCT04546724) These subjects will have annual follow-up visits at Months 12, 24, 36, 48 and 60 after immunization. The primary objective of this study will be to evaluate persistence of antibodies annually from 1 to 5 years after the single immunization with VLA1553. The secondary objective is to evaluate long-term safety 6 months to 2 years after the single immunization with VLA1553.

Official Title
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An Open-Label, Single Arm Study To Evaluate Antibody Persistence And Long Term Safety Of A Live-Attenuated Chikungunya Virus Vaccine Candidate (VLA1553) In Adults Aged 18 Years and Above

Conditions
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Chikungunya Virus Infection

Intervention / Treatment
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* Biological: VLA1553


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subject participated in the VLA1553-301 clinical study; Subject has an understanding of the study and its procedures, agrees to its provisions, and voluntarily gives written informed consent prior to any study-related procedures; Subject had immunogenicity blood samples taken at baseline (Visit 1) and either Day 29 (Visit 3), Day 85 (Visit 4) or Day 180 (Visit 5) in Study VLA1553-301 and was negative for neutralizing antibodies at baseline Exclusion Criteria: Subject presents with clinical conditions representing a contraindication to blood draws; Subject has donated blood or use of blood products prior 30 days of immunogenicity sampling; Subject has received an active drug with potential immunosuppressive action or investigational drug or device within a period of 30 days prior a study visit; Subject has a known or suspected problem with alcohol or drug abuse as determined by the Investigator; Subject has any condition that, in the opinion of the Investigator, may compromise the subject's well-being, might interfere with evaluation of study endpoints, or would limit the subject's ability to complete the study; Subject is committed to an institution (by virtue of an order issued either by the judicial or the administrative authorities); Subject is a member of the team conducting the study or in a dependent relationship with one of the study team members. Dependent relationships include close relatives (i.e., children, partner/spouse, siblings, parents) as well as employees of the Investigator or site personnel conducting the study.

Ages Eligible for Study
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Minimum Age: 18 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
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: VLA1553<br> | Biological: VLA1553<br>* Study participants previously vaccinated with VLA1553 in study VLA1553-301 will be followed up for safety and immunogenicity.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of subjects with a seroprotective CHIKV antibody level post-vaccination. |  | until Year 5 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency of any Serious Adverse Event (SAE) |  | until Year 2 | 
| Relatedness of any Serious Adverse Event (SAE) |  | until Year 2 | 
| Immune r esponse as measured by CHIKV-specific neutralizing antibody titers post-vaccination |  | until Year 5 | 
| Proportion of subjects with seroconversion |  | until Year 5 | 
| Fold increase of CHIKV-specific neutralizing antibody titers post-vaccination as compared to baseline (i.e. at start of study VLA1553-301) |  | until Year 5 | 
| Proportion of subjects reaching an at least 4-fold, 8-fold, 16-fold or 64-fold increase in CHIKV-specific neutralizing antibody titer compared to baseline |  | until 5 Year 5 |