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NCT Number: NCT07163845

Assessment of Chikungunya Virus Seroprevalence Before VLA1553 Vaccination in the Municipalities Selected for Participation in the VLA1553 Pilot Vaccination Strategy in Brazil

This is a cross-sectional serosurvey using household cluster sampling conducted before the VLA1553 pilot vaccination strategy will be implemented in about 10 municipalities in Brazil.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

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Key information

Conditions

Chikungunya Virus Infection Alphavirus Infections Arbovirus Infections Chikungunya Fever Infections Mosquito-Borne Diseases RNA Virus Infections Togaviridae Infections Vector Borne Diseases Virus Diseases

Age range

2 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Universidade Federal Do Ceará, Fortaleza, Ceará, Brazil

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About this study

Households will be selected randomly using a multi-stage random sampling at the census tract, street, and household levels, to select study participants. The study aims to prospectively evaluate the association between vaccination uptake and previous CHIKV exposure (pre-existing immunity to CHIKV infection) in the age-group approved per label in Brazil (e.g., adults [≥18 years of age] or individuals ≥12 years of age). Seroprevalence among vaccinated and unvaccinated individuals will be used to parameterize a probabilistic bias analysis conducted as part of the VE study. Finally, the study will explore the prevalence of CHIKV exposure in the different study communities before the VLA1553 pilot vaccination strategy in individuals ≥2 years of age.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Individuals residing in the selected municipalities of Brazil where the VLA1553 pilot vaccination strategy will be implemented.
  • Individuals ≥2 years of age
  • Individuals who sleep 3 nights a week or more in a household that is selected by cluster sampling.

Exclusion criteria

  • Individuals or their legally accepted representatives (LAR) who are not willing or not able to provide informed consent (and assent, as required) according to country-specific procedures.

Treatment and study plan

Live-attenuated CHIKV vaccine VLA1553

Biological

Non-interventional study: VLA1553 is used in the pilot vaccination strategy which is carried out after this observational study.

Primary outcomes

  1. To prospectively evaluate the association between vaccination uptake and previous CHIKV exposure (pre-existing immunity to CHIKV infection) after implementing a pilot vaccination in the age-group approved per label.

    Time frame: on Day 1

Other outcomes

  1. To evaluate CHIKV seroprevalence in the selected municipalities before the implementation of a pilot vaccination in the population ≥2 years of age

    Time frame: on Day 1

  2. The association, measured as an odds ratio, between vaccination uptake and prevaccination strategy CHIKV seropositivity (IgG)

    Time frame: on Day 1

  3. Pre-vaccination strategy CHIKV seropositivity (IgG) stratified by vaccination status with VLA1553 vaccine, among the population approved per label

    Time frame: on Day 1

  4. Vaccination uptake, measured as cumulative incidence, according to prevaccination strategy CHIKV seropositivity (IgG)

    Time frame: on Day 1

  5. CHIKV seropositivity (IgG) among the study participants ≥2 years of age assessed by rapid diagnostic test (RDT) or Enzyme-Linked Immunosorbent Assay (ELISA) tested on a dried blood spot (DBS) sample before the implementation of the VLA1553 PVS

    Time frame: on Day 1

Sponsors and collaborators

Lead sponsor

Valneva Austria GmbH

Industry

Collaborators

  • Butantan Foundation
  • Coalition for Epidemic Preparedness Innovations

Registry information

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Sep 9, 2025
Registry last updated
Feb 11, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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