Dose-ranging Study of an Investigational Yellow Fever Candidate Vaccine in Adults (VYF01)

September 17, 2025 updated by: Sanofi Pasteur, a Sanofi Company

Safety, Tolerability, and Immunogenicity Dose-ranging Study of the Investigational Yellow Fever Vacine (vYF) Candidate Vaccine in Adults

The primary objectives of the study are:

  • To describe the safety profile of each of the 3 dosages of vYF and of YF-VAX® within the 28 days post-vaccination and up to the 6 months (Day 180) post-vaccination visit
  • To describe the antibody responses elicited by each of the 3 dosages of vYF and by YF-VAX on Day 0 pre-vaccination and then on Day 10, Day 14, Day 28 and 6 months (Day 180) post-vaccination overall and by baseline flavivirus serostatus
  • To quantify the detectable yellow fever (YF) vaccinal viremia in each vaccine groups (vYF and YF-VAX) in a subset of subjects on Day 0 visit, Day 1 visit, Day 3 visit, Day 5 visit, Day 7 visit, Day 10 visit, and Day 14 visit.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

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

Study duration per participant is approximately 6 months.

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.
Interventional

Enrollment (Actual)

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.
73

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

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

  • United States
    • Maryland
      • Silver Spring, Maryland, United States, 20910
        • Investigational Site Number 8400001

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

18 years to 60 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion criteria :

  • Aged 18 years up to 60 years on the day of inclusion
  • Able to read and understand the Informed Consent Form which has been signed and dated
  • Able to attend all scheduled visits and to comply with all trial procedures

Exclusion criteria:

  • Participant is pregnant, or lactating, or of childbearing potential and not using an effective method of contraception or abstinence from at least 4 weeks prior to vaccination until at least 4 weeks after vaccination. To be considered of non-childbearing potential, a female must be pre-menarche , or post-menopausal for at least 1 year, or surgically sterile
  • Participation at the time of study enrollment (or in the 4 weeks preceding the trial vaccination) or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device, or medical procedure
  • Receipt of any vaccine in the 4 weeks preceding the trial vaccination or planned receipt of any vaccine in the 4 weeks following the trial vaccination
  • Previous vaccination against a flavivirus disease including YF with either the trial vaccine or another vaccine
  • Receipt of immune globulins, blood, or blood-derived products in the past 6 months
  • Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy, or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
  • Known history of flavivirus infection
  • Known systemic hypersensitivity to any of the vaccine components, eggs, or history of a life-threatening reaction to the vaccines used in the trial or to a vaccine containing any of the same substances
  • Known history or laboratory evidence of human immunodeficiency virus infection
  • Known history of hepatitis B or hepatitis C seropositivity
  • Personal of family history of thymic pathology (thymoma, thymectomy, or myasthenia)
  • Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
  • Current alcohol abuse or drug addiction
  • Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion, including malignancy, such as leukemia or lymphoma
  • Moderate or severe acute illness/infection (according to investigator judgment) on the day of vaccination or febrile illness (temperature ≥ 100.4 F). A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided
  • Administration of any anti-viral within 2 months preceding the vaccination and up to the 6 weeks following the vaccination
  • Identified as an Investigator or employee of the Investigator or study center with direct involvement in the proposed study, or identified as an immediate family member (ie, parent, spouse, natural or adopted child) of the Investigator or employee with direct involvement in the proposed study
  • Planned travel in a YF endemic country within 6 months of investigational or control vaccine administration

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

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

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
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.
Experimental: Group 1
1 injection of vYF vaccine Dosage 1
Biological: Yellow fever vaccine (produced on serum-free Vero cells), Dosage 1 vYF vaccine
Pharmaceutical form: Powder and diluent for suspension for injection Route of administration: Subcutaneous
Experimental: Group 2
1 injection of vYF vaccine Dosage 2
Biological: Yellow fever vaccine (produced on serum-free Vero cells), Dosage 2 vYF vaccine
Pharmaceutical form: Powder and diluent for suspension for injection Route of administration: Subcutaneous
Experimental: Group 3
1 injection of vYF vaccine Dosage 3
Biological: Yellow fever vaccine (produced on serum-free Vero cells), Dosage 3 vYF vaccine
Pharmaceutical form: Powder and diluent for suspension for injection Route of administration: Subcutaneous
Active Comparator: Group 4
1 injection of YF-VAX
Biological: Yellow fever vaccine
Pharmaceutical form: Powder and diluent for suspension for injection Route of administration: Subcutaneous
Other Names:
  • YF-VAX

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
Number of participants with immediate adverse events
Time Frame: Within 30 minutes after vaccination
Immediate adverse events are any unsolicited systemic adverse events reported in the 30 minutes after vaccination
Within 30 minutes after vaccination
Number of participants with solicited injection site reactions
Time Frame: Within 7 days after vaccination
Solicited injection site reactions include injection site pain, erythema and swelling
Within 7 days after vaccination
Number of participants with solicited systemic reactions
Time Frame: Within 14 days after vaccination
Solicited systemic reactions include fever, headache, malaise, and myalgia
Within 14 days after vaccination
Number of participants with unsolicited adverse events
Time Frame: Within 28 days after vaccination
Unsolicited (spontaneously reported) adverse events not fulfilling criteria for solicited adverse reactions
Within 28 days after vaccination
Number of participants with Grade 3 fever
Time Frame: Within 28 days after vaccination
Grade 3 fever is defined as temperature ≥ 102.1°F
Within 28 days after vaccination
Number of participants with serious adverse events
Time Frame: From Day 0 to Day 180
Serious adverse events are collected throughout the study
From Day 0 to Day 180
Number of participants with hematology and biochemistry out-of-range test results
Time Frame: From Day 0 to Day 14
Hematology and biochemistry values that are out-of-range are assessed
From Day 0 to Day 14
Number of participants with YF and flavivirus viremia and out-of-normal-range biological test results in the event of severe fever, or suspicion of neurotropic disease or acute viscerotropic diseases
Time Frame: Within 28 days after vaccination
Investigators are provided with guidelines for recognition and assessment of potential viscerotropic and neurotropic events
Within 28 days after vaccination
Number of participants with seroconversion to YF virus
Time Frame: From Day 0 to Day 28
Seroconversion is defined as a fourfold increase in neutralizing antibody titers as compared to pre-vaccination value. Seroconversion is assessed from Day 0 (pre-vaccination) to Day 10, Day 14 and Day 28.
From Day 0 to Day 28
Number of participants with neutralizing antibody titers against YF virus above pre-defined threshold
Time Frame: From Day 0 to Day 180
Pre-defined threshold of 10 1/dilution
From Day 0 to Day 180
Geometric mean titers of neutralizing antibodies against YF virus
Time Frame: From Day 0 to Day 180
Geometric mean titer ratio Day 10/Day 0, Day 14/Day 0, Day 28/Day 0 and Day 180/Day 0
From Day 0 to Day 180
Number of participants with YF vaccinal viremia
Time Frame: From Day 0 to Day 14
Vaccinal viremia is measured by YF specific quantitative reverse transcription polymerase chain reaction (RT-PCR) assay in samples collected on Day 0, Day 1, Day 3, Day 5, Day 7, Day 10, and Day 14.
From Day 0 to Day 14
Level of YF vaccinal viremia
Time Frame: From Day 0 to Day 14
Vaccinal viremia is measured by YF specific quantitative RT-PCR assay in samples collected on Day 0, Day 1, Day 3, Day 5, Day 7, Day 10, and Day 14.
From Day 0 to Day 14

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.
Sanofi Pasteur, a Sanofi Company

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Clinical Sciences & Operations, Sanofi Pasteur, a Sanofi Company

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

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.
January 15, 2020

Primary Completion (Actual)

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.
June 24, 2021

Study Completion (Actual)

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.
June 24, 2021

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).
October 25, 2019

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.
October 25, 2019

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.
October 29, 2019

Study Record Updates

Last Update Posted (Estimated)

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.
September 22, 2025

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.
September 17, 2025

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.
September 1, 2025

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.
  • VYF01
  • U1111-1217-1958 (Other Identifier: UTN)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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