CompletedPhase 3

Phase 3 Randomized, Modified Double-blind, Active-controlled Safety Study on vYF in Adults

United States640 participantsStarted 2025-05-22

Plain-language summary

The purpose of this study is to assess the safety of vYF (investigational vaccine) compared to the safety of YF-VAX (YF licensed vaccine) in adults aged 18 years up to 60 years. Study details include: * The study duration will be up to approximately 6 months. * One single dose of the study intervention (vYF or YF-VAX) will be administered subcutaneously at the 1st visit. * The visit(V) frequency will be Day(D) 01 (V01) and D29 (V02). Two telephone calls will be planned at D15 and Month(M)6. Number of Participants: A total of 640 participants are expected to be included in the study in a 3:1 ratio (vYF: YF-VAX): Group 1: vYF; N=480 Group 2: YF-VAX; N=160 Study Arms and Duration: Randomized, active control (YF-VAX). 6 months duration per participants. Eligible participants will be randomized in a 3:1 ratio to receive, subcutaneously, a single dose of vYF or YF-VAX vaccines on D01.

Who can participate

Age range

18 Years – 59 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

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 12 weeks after study intervention administration.

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Number of participants with immediate adverse events

Timeframe: Within 30 minutes after vaccination

Number of participants with solicited injection site reactions

Timeframe: Up to 7 days after vaccination

Number of participants with solicited systemic reactions

Timeframe: Up to 14 days after vaccination

Number of participants with unsolicited adverse events (AEs)

Timeframe: Up to 28 days after vaccination

Number of participants with medical attended adverse events (MAAEs)

Timeframe: Up to 28 days after vaccination

Number of participants with adverse events of special interest (AESIs)

Timeframe: Up to 6 months after vaccination

Number of participants with serious adverse events (SAEs)

Timeframe: Up to 6 months after vaccination

Trial details

NCT IDNCT07002060

SponsorSanofi

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2026-01-20

View on ClinicalTrials.gov More Yellow Fever Immunization trials

Plain-language summary

Who can participate

Age range

18 Years – 59 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

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 12 weeks after study intervention administration.

What they're measuring

Number of participants with immediate adverse events

Timeframe: Within 30 minutes after vaccination

Number of participants with solicited injection site reactions

Timeframe: Up to 7 days after vaccination

Number of participants with solicited systemic reactions

Timeframe: Up to 14 days after vaccination

Number of participants with unsolicited adverse events (AEs)

Timeframe: Up to 28 days after vaccination

Number of participants with medical attended adverse events (MAAEs)

Timeframe: Up to 28 days after vaccination

Number of participants with adverse events of special interest (AESIs)

Timeframe: Up to 6 months after vaccination

Number of participants with serious adverse events (SAEs)

Timeframe: Up to 6 months after vaccination