Observational Study to Assess the Effectiveness of VLA1553 Vaccine in Preventing Chikungunya During a Pilot Vaccination Strategy in Brazil

February 9, 2026 updated by: Valneva Austria GmbH

A Test-Negative Case-control Study to Evaluate the Effectiveness of VLA1553 Against Chikungunya Virus Disease During a Pilot Vaccination Strategy in Brazil

This is an observational, non-interventional, test-negative case-control (TNCC) study to estimate the vaccine effectiveness of VLA1553 against Chikungunya virus in a real-world setting.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Enrolling by invitation

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The objective of this study is to evaluate the effectiveness of vaccination with VLA1553 in the prevention of laboratory-confirmed symptomatic cases of CHIK after a single dose of VLA1553 administered as part of a pilot vaccination strategy following licensure in Brazil.

The study will commence following the implementation of the pilot vaccination strategy in selected municipalities. Data for the analyses will be obtained from official Brazilian Ministry of Health surveillance systems, specifically the GAL (Laboratory Environment Management System), SINAN (Notifiable Diseases Information System), and Si-PNI (National Immunization Program Information System).

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
1200

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Valneva Late-Stage Clinical Development
  • Phone Number: +43 1 206 20 0
  • Email: office@valneva.com

Study Locations

  • Brazil
    • Ceará
      • Fortaleza, Ceará, Brazil, 60430-160
        • Universidade Federal Do Ceara
    • Minas Gerais
      • Belo Horizonte, Minas Gerais, Brazil, 31270-901
        • Universidade Federal de Minas Gerais, CT Terapias Avançadas e Inovadoras
    • Sergipe
      • Laranjeiras, Sergipe, Brazil, 49060-025
        • Centro de Pesquisas Clínicas Universidade Federal Sergipe, Hospital e Maternidade São João de Deus
    • São Paulo
      • São Pedro, São Paulo, Brazil, 15090-000
        • Fundacao Faculdade Regional de Medicina de Sao Jose Do Rio Preto

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Residents of the selected areas, within the age limits approved for the PVS, presenting at the health care facilities during the study period.

Description

Inclusion Criteria:

  1. Have place of residence in a municipality where the pilot vaccination strategy is implemented;
  2. Are in an eligible age-group to receive the VLA1553 vaccine;
  3. Have been notified in SINAN as a suspected case for CHIK or Dengue surveillance during the study period;
  4. Have a sample registered in GAL that is collected within 0-5 days following the onset of CHIKV-like symptoms and is tested for CHIKV using RT-PCR;
  5. Have complete data in the Brazilian MoH databases (SINAN and GAL) on age, sex, municipality of residence, sample collection date, and date of symptom onset and the healthcare facilities where the suspected case was reported.

Exclusion Criteria:

  1. Have inconclusive RT-PCR result for CHIKV;
  2. Have the first CHIKV-like symptom onset less than 14 days from date of vaccination.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Cases: Test-positive for Chikungunya virus
Biological: Live-attenuated CHIKV vaccine VLA1553
Non-interventional study: VLA1553 is used in the pilot vaccination strategy which is linked to this observational study.
Controls: Test-negative for Chikungunya virus
Biological: Live-attenuated CHIKV vaccine VLA1553
Non-interventional study: VLA1553 is used in the pilot vaccination strategy which is linked to this observational study.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Detection of CHIKV in VLA1553-vaccinated (≥14 days after vaccination) and unvaccinated study individuals with CHIKV-like symptoms confirmed by reverse transcriptase polymerase chain reaction (RT-PCR).
Time Frame: Study start through study completion, an average of 23 months
Study start through study completion, an average of 23 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Detection of CHIKV in VLA1553-vaccinated (≥14 days after vaccination) and unvaccinated study individuals ≥50 years of age with CHIKV-like symptoms confirmed by RT-PCR.
Time Frame: Study start through study completion, an average of 23 months
Study start through study completion, an average of 23 months

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Time Frame
Detection of CHIKV in VLA1553-vaccinated (≥14 days after vaccination) and unvaccinated individuals with CHIKV-like symptoms confirmed by RT-PCR, stratified by sex and age group (≥18 to 59 and ≥ 60 years, depending on the age group approved for the PVS)
Time Frame: Study start through study completion, an average of 23 months
Study start through study completion, an average of 23 months
Detection of CHIKV in VLA1553-vaccinated (≥14 days after vaccination) and unvaccinated study individuals with CHIKV-like symptoms confirmed by RT-PCR, stratified by time since vaccination (from 0 to 6 months after Day 15)
Time Frame: Study start through study completion, an average of 23 months
Study start through study completion, an average of 23 months
CHIKV hospitalizations (confirmed by RT-PCR) in VLA1553-vaccinated (≥14 days after vaccination) and unvaccinated study individuals; CHIKV deaths (confirmed by RT-PCR) in VLA1553-vaccinated (≥14 days after vaccination) and unvaccinated study individuals
Time Frame: Study start through study completion, an average of 23 months
Study start through study completion, an average of 23 months
Magnitude and direction of estimated level of bias due to unmeasured pre-vaccination strategy CHIKV infection, and estimated VE corrected for this bias.
Time Frame: Study start through study completion, an average of 23 months
Study start through study completion, an average of 23 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Valneva Austria GmbH

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Coalition for Epidemic Preparedness Innovations
Fundação Butantan

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 2, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 4, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 7, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 16, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 11, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 9, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • VLA1553-402

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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