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

A Phase 1, Randomized, Multi-center Study to Evaluate the Safety and Immunogenicity of Different Formulations of Vaccines Encoding the RSV Monovalent Antigen or the Flu H5 Antigen in Healthy Participants 18 to 49 Years of Age

Study of Different Formulations of Vaccines Encoding the RSV Monovalent Antigen or the Flu H5 Antigen in Participants 18 to 49 Years of Age (NCT07516418) is a Phase 1 interventional studying Respiratory Syncytial Virus (RSV) and Influenza A(H5N1), sponsored by Sanofi. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

About This Trial

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.

What Stage of Research Is This?

Phase 1 trials test a new treatment for the first time in humans, focusing on safety, dosing, and how the body processes the drug. For Respiratory Syncytial Virus (RSV), a Phase 1 study typically enrolls a small number of participants — often healthy volunteers or patients who have exhausted standard treatment options. Phase 1 results determine whether a treatment moves into larger Phase 2 efficacy studies.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

A target enrollment of 570 participants makes this a sizable late-stage trial. Studies in this range typically have enough power to detect clinically meaningful differences from a comparator and to characterize less-common side effects.

Who May Be Eligible (Plain English)

Who May Qualify: - 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. Who Should NOT Join This Trial: • 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. Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language

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.