Phase 3 Single Arm, Open Study on vYF in Adults

NCT07222059 | Completed Phase 3 DMC

• 1 other identifier: VYF00011
• Study Type: interventional
• Target: 254
• Locations: 1 country
• Sites: 4

Brief Summary

The purpose of this study is to assess the safety and immunogenicity of vYF in adults aged 18 years and over in Japan. Study details include:

• The study duration will be up to approximately 1 month.
• One single dose of vYF will be administrated subcutaneously at the 1st visit.
• The visit frequency will be Day 01 (Visit 01) and Day 29 (Visit 02). One telephone call (TC) will be planned at Day 15. Number of Participants: A total of 254 participants is expected to be included in the study with the aim to obtain a total of 203 evaluable participants. Study Arms and Duration: Eligible participants will receive, subcutaneously, a single dose of vYF vaccine on Day 1. The duration of each participation will be approximately 1 month for each participant.

Conditions

Yellow Fever

Outcome Measures

Primary Outcomes (1)

• Percentage of participants with seroconversion to YF virus in YF-naive participants

  Seroconversion rates will be assessed using a YF MN assay Seroconversion is defined as a 4-fold increase in neutralizing Ab (NAb) titers as compared to the pre-vaccination value (Day 01)

  28 days after one dose of vYF vaccine

Secondary Outcomes (10)

• Percentage of participants with seroprotection to YF virus

  At Day 01 and Day 29

• Percentage of participants with seroconversion to YF virus

  28 days after one dose of vYF vaccine

• Geometric Mean Titers (GMTs) of neutralizing antibodies against YF virus

  At Day 01 and Day 29

• Geometric Mean Titers Ratio (GMTRs) of neutralizing antibodies against YF virus

  At Day 01 and Day 29

• Number of participants with immediate adverse events

  Within 30 minutes after vaccination

Study Arms (1)

vYF

EXPERIMENTAL

One single dose of vYF will be administered subcutaneously at the 1st visit

Biological: Yellow fever vaccine (live)

Interventions

Yellow fever vaccine (live) BIOLOGICAL

Pharmaceutical form:Powder and diluent for suspension for injection-Route of administration:Subcutaneous

Also known as: vYF vaccine

vYF

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• \* "From 18 years" means from the day of the 18th birthday
• Participants who are healthy as determined by medical evaluation including medical history and physical examination.
• Able to attend all scheduled visits and to comply with all study procedures
• A female participant is eligible to participate if she is not pregnant or breastfeeding and one of the following conditions applies:
• Is of non-childbearing potential. To be considered of non-childbearing potential, a female must be postmenopausal for at least 1 year, or surgically sterile.
• Is of childbearing potential and agrees to use an effective contraceptive method or abstinence from at least 4 weeks prior to study intervention administration until at least 4 weeks after study intervention administration.
• A female participant of childbearing potential must have a negative highly sensitive pregnancy test (urine or serum as required by local regulation) before any dose of study intervention on Day 01 and will be repeated on Day 29 to confirm the participant is still not pregnant within the 28 days of vaccine administration.

You may not qualify if:

• Participants are excluded from the study if any of the following criteria apply:
• 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 or laboratory evidence of HIV infection.
• Known history of hepatitis B or hepatitis C seropositivity
• Known history of FV infection, Japanese encephalitis (JE) excluded
• Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccines used in the study or to a vaccine containing any of the same substances
• Personal or family history of thymic pathology (thymoma, thymectomy, or myasthenia).
• 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
• \* Chronic illness may include, but is not limited to cardiac disorders, renal disorders, auto-immune disorders, diabetes, psychiatric disorders or chronic infection
• Moderate or severe acute illness/infection (according to Investigator judgment) on the day of vaccination or febrile illness (temperature ≥ 37.5°C \[or ≥ 99.5°F\]). A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided.
• Alcohol, prescription drug, or substance abuse that, in the opinion of the Investigator, might interfere with the study conduct or completion.
• Receipt of any vaccine in the 4 weeks preceding the study vaccination or planned receipt of any vaccine in the 4 weeks following the study vaccination (prior to Visit 2 on Day 29), except for influenza vaccination, which may be received at least 2 weeks before study vaccines. This exception includes pandemic influenza vaccines including monovalent pandemic influenza vaccines.
• Previous vaccination against YF.
• Receipt of immune globulins, blood, or blood-derived products in the past 6 months.
• Administration of any anti-viral within 2 months preceding the vaccination and up to the 6 weeks following the vaccination.

Sponsors & Collaborators

• Sanofi Pasteur, a Sanofi Company: lead

Study Sites (4)

Investigational Site Number : 3920001

Takatsuki, Osaka, 569-1192, Japan

Location

Investigational Site Number : 3920002

Chūō, Tokyo, 103-0025, Japan

Location

Investigational Site Number : 3920003

Shinjuku-ku, Tokyo, 169-0072, Japan

Location

Investigational Site Number : 3920004

Taitō City, Tokyo, 111-0036, Japan

Location

Related Links

• VYF00011 Plain Language Results Summary

MeSH Terms

Conditions

Yellow Fever

Interventions

Yellow Fever Vaccine

Condition Hierarchy (Ancestors)

Mosquito-Borne Diseases; Vector Borne Diseases; Infections; Arbovirus Infections; Virus Diseases; Flavivirus Infections; Flaviviridae Infections; RNA Virus Infections; Hemorrhagic Fevers, Viral

Intervention Hierarchy (Ancestors)

Viral Vaccines; Vaccines; Biological Products; Complex Mixtures

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: NA
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: October 27, 2025
• First Posted: October 29, 2025
• Study Start: October 23, 2025
• Primary Completion: December 25, 2025
• Study Completion: December 25, 2025
• Last Updated: February 3, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will share

Locations

JP (4)