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

Enrolling by invitation

Conditions

Intervention / Treatment

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

Observational

Enrollment (Estimated)

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 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
        • Fundação Faculdade Regional de Medicina de São José 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

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
Intervention / Treatment
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

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

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

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

Valneva Austria GmbH

Collaborators

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)

February 2, 2026

Primary Completion (Estimated)

December 31, 2027

Study Completion (Estimated)

December 31, 2027

Study Registration Dates

First Submitted

December 4, 2025

First Submitted That Met QC Criteria

January 7, 2026

First Posted (Actual)

January 16, 2026

Study Record Updates

Last Update Posted (Actual)

February 11, 2026

Last Update Submitted That Met QC Criteria

February 9, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID 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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