VLA1553-403 Pregnancy Surveillance Study

July 16, 2026 updated by: Valneva Austria GmbH

Observational Study to Evaluate the Safety of Live-attenuated Chikungunya Virus Vaccine (VLA1553) in Pregnant Women Exposed to the Vaccine in Brazil

This post-marketing, observational study evaluates pregnancy and infant outcomes up to 12 weeks after delivery among women who received the chikungunya vaccine (VLA1553) during pregnancy or within 30 days before their last menstrual period. A matched comparator cohort of pregnant women vaccinated with routine, pregnancy-recommended vaccines (not exposed to VLA1553) is included. No study procedures beyond routine care are performed.

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

This is an observational, non-interventional study in pregnant women who were vaccinated with the live-attenuated chikungunya virus vaccine (VLA1553) anytime during their pregnancy or within 30 days preceding their last menstrual period (VLA1553 group). The study protocol includes a comparator group of routinely vaccinated pregnant women not exposed to VLA1553 (control group).

The VLA1553 and control groups will be matched by gestational trimester and maternal age range (women <35 years of age at the time of enrolment and women >35 years of age) at exposure time. The study will collect information including vaccine exposure, demographic information, pregnancy data (e.g., date of positive pregnancy test, expected delivery date, previous pregnancy information), and medical history. Furthermore, data on pregnancy and infant outcomes up to 12 weeks post expected delivery date (EDD) will be compiled. The EDD will be calculated by counting 40 weeks from the first day of the LMP. This approach involves collecting data from the participating women onto the database by site staff and, if possible, confirmed and expanded by their PS-HCP as needed. Additionally, with consent, medical records may be accessed by study staff to further verify and supplement the information. This study will not provide or make recommendations on any vaccine use. Participation in the study is voluntary. Participation or lack of participation in this study will not change or influence a participant's standard of care.

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.
200

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
    • 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

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
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The control group will consist of women who have received vaccine(s) approved for use during pregnancy by the MoH and who meet the matching criteria.

Description

Inclusion Criteria:

VLA1553 vaccinated population:

  • Women who have received the single dose of the VLA1553 vaccine during pregnancy or within the 30 days prior to the first day of the last menstrual period.
  • Pregnant at the time of enrolment in the study.
  • The participant understands and agrees to comply with the study procedures.

Control group:

  • Pregnant at the time of enrolment in the study.
  • Women who have received vaccine(s) approved for use during pregnancy by the MoH and who meet the matching criteria described in the protocol.
  • The participant understands and agrees to comply with the study procedures.
  • Women who have not received the VLA1553 vaccine during pregnancy or within the 30 days prior to the first day of the last menstrual period.

Exclusion Criteria:

  • Women who do not provide informed consent.
  • Women who are not part of the target population of the pilot vaccination strategy at the time 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.
VLA1553 group
Women vaccinated with the chikungunya virus vaccine (VLA1553) anytime during their pregnancy or within 30 days preceding their last menstrual period.
Biological: Live-attenuated CHIKV vaccine VLA1553
Non-interventional study: VLA1553 is used in the pilot vaccination strategy which will start along with this observational study.
Control group
Women who have received vaccine(s) approved for use during pregnancy by the MoH and who meet the matching criteria.
Biological: Vaccine(s) approved for use during pregnancy by the MoH
Vaccine(s) approved for use during pregnancy by the MoH

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
Measure Description
Time Frame
Frequency (n,%) of individuals with any outcome (pregnancy and infant health), as described in the protocol.
Time Frame: Study start through study completion, an average of 12 months

Pregnancy and infant outcomes will be collected as follows:

  1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births.
  2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Frequency (n,%) of specific outcomes (pregnancy and infant health), as described in the protocol.
Time Frame: Study start through study completion, an average of 12 months

Pregnancy and infant outcomes will be collected as follows:

  1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births.
  2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 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
Measure Description
Time Frame
Frequency (n,%) of individuals with any outcome (pregnancy and infant health), as described in the protocol in the VLA1553 group and the control group.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Frequency (n,%) of specific outcomes (pregnancy and infant health), as described in the protocol in the VLA1553 group and the control group.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Relative risk (RR) of any outcome (pregnancy and infant health) between pregnant women vaccinated with VLA1553 and pregnant women vaccinated with other vaccines recommended during pregnancy, as described in the protocol.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 months
Frequency (n,%) of individuals with SAEs (women and infants), following vaccination with VLA1553 or a control vaccine.
Time Frame: Study start through study completion, an average of 12 months
Pregnancy and infant outcomes will be collected as follows: 1. Pregnancy outcomes: stillbirths, pregnancy terminations (spontaneous and elective), preterm deliveries, neonatal deaths and term live births. 2. Infant outcomes: births small for gestational age, major congenital malformations.
Study start through study completion, an average of 12 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
Butantan Foundation

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.
June 11, 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).
February 9, 2026

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.
February 9, 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.
February 17, 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.
July 20, 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.
July 16, 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.
July 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.
  • VLA1553-403

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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