Skip to main content
OpenTrials
Enrolling by Invitation

NCT Number: NCT07347002

Observational Study to Assess the Effectiveness of VLA1553 Vaccine in Preventing Chikungunya 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.

Enrolling by Invitation

Interested in participating?

Request Info

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

18 year–59 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Universidade Federal de Minas Gerais, CT Terapias Avançadas e Inovadoras, Belo Horizonte, Minas Gerais, Brazil

Loading trial locations.

About this study

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).

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Have a CHIKV RT-PCR result registered from a municipality where the pilot vaccination strategy is implemented and is in scope of the VLA1553-402 study;
  • Are in an eligible age-group to receive the VLA1553 vaccine;
  • Have been notified in SINAN as a suspected case for CHIK or Dengue surveillance during the study period;
  • 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;
  • 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

  • Have inconclusive RT-PCR result for CHIKV;
  • Have a detectable vaccine virus identified via sequencing;
  • For vaccinated and CHIV RT-PCR positive individuals, have no valid sequencing result available for RT-PCR positive samples collected within 30 days post-vaccination;
  • Have the first CHIKV-like symptom onset less than 14 days from date of vaccination.

Treatment and study plan

Live-attenuated CHIKV vaccine VLA1553

Biological

Non-interventional study: VLA1553 is used in the pilot vaccination strategy which is linked to this observational study.

Primary outcomes

  1. 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

Secondary outcomes

  1. 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

Other outcomes

  1. 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

  2. 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

  3. 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

  4. 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

Sponsors and collaborators

Lead sponsor

Valneva Austria GmbH

Industry

Collaborators

  • Butantan Foundation
  • Coalition for Epidemic Preparedness Innovations

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Jan 16, 2026
Registry last updated
Jul 17, 2026

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

View the official ClinicalTrials.gov record (opens in a new tab)

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.

Related clinical trials

Published trials that share one or more normalized conditions with this study.