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NCT Number: NCT07254702

Prospective Safety Cohort Study After VLA1553 Vaccination in Municipalities Selected for Participation in the VLA1553 Pilot Vaccination Strategy in Brazil

This is an observational study with primary data collection, which will combine a prospective safety cohort study and an SCRI study.

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

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

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

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About this study

This prospective safety cohort study will be conducted in selected Brazilian municipalities participating in a pilot vaccination strategy. A total of 5,000 participants will be recruited. The primary objective is to estimate the incidence rates of a predefined set of AEs which constitute safety concerns. The secondary objectives are to measure the relative risk associated with VLA1553 administration for a predefined set of AEs which constitute safety concerns, and to assess the frequency of occurrence of any collected AE which are medically attended or meet the criteria of seriousness This study also aims to investigate VLA1553's safety in underrepresented populations by collecting all AEs, not just AEs which constitute safety concerns.

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Male or female participants who received a single dose of VLA1553 at a vaccination unit while participating in the pilot vaccination strategy.
  • Individuals that are target for the pilot vaccination strategy at the time of vaccination.
  • Individuals understanding and being able to comply with all scheduled follow-up calls/contacts and study procedures.
  • Have given informed consent/assent prior to entering the study.

Exclusion criteria

  • Individuals who have received investigational products within the 30 days prior to VLA1553 vaccination, or individuals who have received VLA1553/IXCHIQ previously or any authorized or approved CHIKV vaccine.
  • Individuals who are not expected to remain available for the study follow-up for the next 24 weeks after vaccination.
  • Pregnant women: women exposed to VLA1553 anytime during their pregnancy or within 30 days preceding their last menstrual period will be invited to participate in a separate pregnancy surveillance study (study identifier VLA1553-403).

Treatment and study plan

Live-attenuated CHIKV vaccine VLA1553

Biological

Non-interventional study: VLA1553 is used in the pilot vaccination strategy which will start along with this observational study.

Primary outcomes

  1. To estimate the incidence rates of a predefined set of AEs which constitute safety concerns according to the VLA1553 Risk Management Plan following the administration of the live-attenuated VLA1553 vaccine

    Time frame: From enrollment until Day 60

    For each safety concern, the risk windows after VLA1553 administration are defined as:

    • 30 days for Chikungunya-like adverse reactions;
    • 60 days for cardiac events, choosing a more conservative window than the 42 days suggested by the Brighton Collaboration recommendations on myocarditis;
    • 60 days for arthritis to account for late-onset or potentially immune-mediated cases

Secondary outcomes

  1. To measure the relative risk associated with VLA1553 administration for a predefined set of AEs which constitute safety concerns as per the VLA1553 Risk Management Plan for those AEs that have a defined risk window following vaccination.

    Time frame: From enrollment until Day 120

  2. To assess the frequency of occurrence of predefined AEs which are medically attended or meet the criteria of seriousness.

    Time frame: From enrollment until Month 6

    • Frequency of occurrence of predefined chronic chikungunya-like adverse reactions;
    • frequency of predefined SAEs;
    • frequency of occurrence of arthralgia;
    • frequency of occurrence of prolonged arthralgia;
    • frequency of predefined CHIKV infection symptoms;
    • frequency of occurrence of predefined chronic CHIKV infection symptoms

Other outcomes

  1. To assess the frequency of occurrence of AEs (not exclusively those of safety concern) following VLA1553 vaccination when co-administered or concomitantly administered with other vaccines.

    Time frame: From enrollment until Month 6

  2. To assess the frequency of occurrence of AEs (not exclusively those of safety concern) in populations underrepresented or excluded in clinical trials with VLA1553.

    Time frame: From enrollment until Month 6

    • Individuals aged ≥ 65 years old (including those with chronic medical conditions);
    • individuals with acute or progressive, unstable, or uncontrolled clinical conditions;
    • individuals with autoimmune or inflammatory disorders (including with impaired or dysregulated immune responses);

Sponsors and collaborators

Lead sponsor

Valneva Austria GmbH

Industry

Collaborators

  • Butantan Foundation
  • Coalition for Epidemic Preparedness Innovations

Registry information

Official study title

Prospective Safety Cohort Study VLA1553-406

Important dates

Study start
2026
Primary completion
2026
Study completion
2027
First posted
Nov 28, 2025
Registry last updated
Jul 21, 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.

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