CompletedPhase 1/2

Study of a Respiratory Syncytial Virus Candidate Encapsulated in a Lipid Nanoparticle Based Formulation in Adults Aged 18 to 50 Years and 60 Years and Older

United States, Australia, Puerto Rico865 participantsStarted 2022-11-17

Plain-language summary

Brief Summary of Stage 1: The purpose of Stage 1 (Phase I/IIa) was to assess the safety and immunogenicity of a single intramuscular (IM) injection of 3 dose-levels of an Respiratory Syncytial Virus (RSV) vaccine candidate formulated with 2 different lipid nanoparticles (LNPs) in healthy adult participants aged between 18 to 50 years, and 60 years and older. The primary objectives of this stage were to assess the safety and immunogenicity profiles across the dose-level groups (low, medium, and high doses) with 2 LNPs. This stage evaluated the safety and immunogenicity of a booster vaccination administered 12 months after the primary vaccination in a subset of the study population. Brief Summary of Stage 2: The study also incorporated a Stage 2 (Phase IIa, dose-ranging design) that included adults aged 60 years and older to assess the safety and immunogenicity of different doses of RSV vaccine encapsulated in one of the LNPs. In the Phase IIa dose-ranging stage, eligible participants were randomly assigned in a 1:1:1 ratio to receive a single IM administration of RSV vaccine candidate doses, or placebo. Multiple safety analyses were performed, minimally at D07 and D28.

Who can participate

Age range

18 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: * Sentinel Cohort Stage 1: Aged 18 to 50 years on the day of inclusion * Main Cohort Stage 1 and Stage 2: Aged 60 years or older on the day of inclusion Stage 1 and Stage 2: * Sentinel Cohort: A female participant was eligible to participate if she was not pregnant or breastfeeding and: * Was of non-childbearing potential. To be considered of non-childbearing potential, a female must have been postmenopausal for at least 1 year or surgically sterile OR * Was 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. * Main and Booster Cohorts: A female participant was eligible to participate if she was not pregnant or breastfeeding and: * Was of non-childbearing potential. To be considered of non-childbearing potential, a female must have been postmenopausal for at least 1 year or surgically sterile. * Able to attend all scheduled visits and to comply with all study procedures * Informed consent form was been signed and dated Exclusion Criteria: * 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 systemic hyperse…

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

Stage 1 (Sentinel and Main Cohort) and Stage 2: Number of Participants With Immediate Unsolicited Systemic Adverse Events (AEs)

Timeframe: Up to 30 minutes post-primary vaccination on Day 1

Stage 1 (Sentinel and Main Cohort) and Stage 2: Number of Participants With Solicited Injection Site Reactions and Systemic Reactions

Timeframe: From Day 1 (first dose of primary vaccination) up to Day 8 (7 days post-primary vaccination on Day 1)

Stage 1 (Sentinel and Main Cohort) and Stage 2: Number of Participants With Unsolicited Adverse Events

Timeframe: From Day 1 (first dose of primary vaccination) up to Day 29 (28 days post-primary vaccination on Day 1)

Stage 1 (Sentinel and Main Cohort): Number of Participants With Medically Attended Adverse Events (MAAEs)

Timeframe: From Day 1 (first dose of primary vaccination) up to Day 29 (28 days post-primary vaccination on Day 1)

Stage 2: Number of Participants With Medically Attended Adverse Events

Timeframe: From Day 1 (first dose of primary vaccination) to Day 180

Stage 1 (Sentinel and Main Cohort) and Stage 2: Number of Participants With Serious Adverse Events (SAEs) and Adverse Events of Special Interest (AESIs)

Trial details

NCT IDNCT05639894

SponsorSanofi Pasteur, a Sanofi Company

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2025-05-02

Results submitted2026-07-10

View on ClinicalTrials.gov More Respiratory Syncytial Virus Immunization trials