RecruitingPhase 1

Study of Different Formulations of Vaccines Encoding the RSV Monovalent Antigen or the Flu H5 Antigen in Participants 18 to 49 Years of Age

Australia570 participantsStarted 2026-04-15

Plain-language summary

The purpose of this study is to evaluate the safety and immunogenicity of different formulations of vaccines encoding the RSV monovalent antigen or the Flu hemagglutinin subtype 5 (H5) antigen in healthy participants aged 18 to 49 years. The total duration of study participation for each participant varies by stage and treatment arm. Stage 1: * For Arm 1, Arm 2, and Arm 3 the duration of study participation will be approximately 7 months for each participant. * For Arm 4, Arm 5, and Arm 6 the duration of study participation will be approximately 6 months for each participant. Stage 2: For all arms, the duration of study participation will be approximately 7 months for each participant.

Who can participate

Age range

18 Years – 49 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: * Aged 18 to 49 years on the day of inclusion * A female participant is eligible to participate if she is not pregnant or breastfeeding and of the following conditions applies: * Is of NCBP (Non-Child-Bearing Potential). To be considered of NCBP, a female must be post-menopausal for at least 1 year, or surgically sterile. OR * Is of CBP (Child-Bearing Potential) and uses an effective contraceptive method or abstinence from at least 4 weeks prior to study intervention administration until at least 12 weeks after the last study intervention administration. Exclusion Criteria: • Any condition which, in the opinion of the Investigator, might interfere with the evaluation of the study objectives The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

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

Presence of any unsolicited systemic Adverse Events (AEs) reported within 30 minutes after vaccination

Timeframe: On Day 1

Presence of solicited injection site reactions (ie, injection site pain, injection site erythema, injection site swelling, pre-listed in participant's diary and in the eCRF (electronic case report form)) occurring through 7 days after each vaccination

Timeframe: Day 1 through day 8

Presence of solicited systemic reactions (ie, fever, headache, and only new or worsened fatigue, myalgia, arthralgia, and chills pre-listed in the participant's diary and in the eCRF) occurring through 7 days after each vaccination

Timeframe: Day 1 through day 8

Presence of unsolicited AEs reported through 20 days after the first vaccination and after the second vaccination for IMPs with the Flu H5 antigen

Timeframe: Day 1 through day 21

Presence of unsolicited AEs reported through 28 days after vaccination for IMPs with the RSV antigen

Timeframe: Day 1 through day 29

Presence of SAEs (Serious Adverse Events) and AESIs (Adverse Events of Special Interest) throughout the study (ie, through 6 months after vaccination)

Trial details

NCT IDNCT07516418

SponsorSanofi

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2027-04-04

Contact for this trial

Sanofi Trial Transparency Email Recommended (Toll free for US and Canada)

800-633-1610 contact-us@sanofi.com

View on ClinicalTrials.gov More Respiratory Syncytial Virus (RSV) trials

Plain-language summary

Who can participate

Age range

18 Years – 49 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.

What they're measuring

Presence of any unsolicited systemic Adverse Events (AEs) reported within 30 minutes after vaccination

Timeframe: On Day 1

Timeframe: Day 1 through day 8

Presence of unsolicited AEs reported through 20 days after the first vaccination and after the second vaccination for IMPs with the Flu H5 antigen

Timeframe: Day 1 through day 21

Presence of unsolicited AEs reported through 28 days after vaccination for IMPs with the RSV antigen

Timeframe: Day 1 through day 29

Presence of SAEs (Serious Adverse Events) and AESIs (Adverse Events of Special Interest) throughout the study (ie, through 6 months after vaccination)