Study of a Respiratory Syncytial Virus mRNA Candidate With 2 Different Lipid Nanoparticle-based Formulations in Adults Aged 18 to 50 Years and 60 Years and Older

The purpose of this study is to assess the safety and immunogenicity of a single intramuscular (IM) injection of 3 dose-levels of a respiratory syncytial virus (RSV) messenger ribonucleic acid (mRNA) vaccine candidate formulated with 2 different lipid nanoparticles (LNPs) (ie, LNP containing CL-0059 or CL-0137) in healthy adult participants aged between 18 and 50 years, and 60 years and older. The primary objectives of this study are to assess the safety and immunogenicity profiles across the dose-level groups (low, medium, and high doses) with 2 LNPs (CL-0059 and CL-0137). In addition, the study will evaluate the safety and immunogenicity of a booster vaccination administered 12 months after the primary vaccination in a subset of the study population. The duration of each participant's participation is 12 months for the Sentinel and Main Cohorts and 24 months overall for the subset of participants enrolled in the Booster Cohort.

Inclusion Criteria:Sentinel Cohort: Aged 18 to 50 years on the day of inclusionMain Cohort: Aged 60 years or older on the day of inclusionSentinel Cohort: A female participant is eligible to participate if she is not pregnant or breastfeeding and: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 ORIs 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 is eligible to participate if she is not pregnant or breastfeeding and: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.Able to attend all scheduled visits and to comply with all study proceduresInformed consent form has been signed and datedExclusion 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 hypersensitivity to any of the study intervention components (eg, polyethylene glycol, polysorbate); history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances; any allergic reaction (eg, anaphylaxis) after administration of mRNA COVID-19 vaccineHistory of RSV-associated illness, diagnosed clinically, serologically, or microbiologically in the last 12 monthsPrevious history of myocarditis, pericarditis, and/or myopericarditisThrombocytopenia or bleeding disorder, contraindicating IM injection based on investigator's judgmentBleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular injectionChronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completionAlcohol, prescription drug, or substance abuse that, in the opinion of the investigator, might interfere with the study conduct or completionReceipt of any vaccine other than mRNA vaccine in the 4 weeks preceding any study intervention administration or planned receipt of any vaccine other than mRNA vaccine in the 4 weeks following any study intervention administrationReceipt of any mRNA vaccine in the 60 days preceding any study intervention administration or planned receipt of any mRNA vaccine in the 60 days following any study intervention administrationPrevious vaccination against RSV with an investigational vaccineReceipt of immune globulins, blood, or blood-derived products in the past 3 monthsReceipt of oral or injectable antibiotic therapy within 72 hours prior to the first blood drawParticipation at the time of study enrollment (or in the 4 weeks preceding the first study intervention administration) or planned participation during the present study period in another clinical study investigating a vaccine, drug, medical device, or medical procedureDeprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarilySelf-reported or documented human immunodeficiency virus (HIV) detected by any FDA-approved/validated test, hepatitis B virus surface antigen (HBsAg), hepatits B core antibodies (HBcAb), or hepatitis C virus antibodies (HCV Abs), or positive SARS-CoV-2 RT-PCR or antigen testIdentified as an investigator or employee of the investigator or study center with direct involvement in the proposed study, or identified as an immediate family member (ie, parent, spouse, natural or adopted child) of the investigator or employee with direct involvement in the proposed studyThe above information is not intended to contain all considerations relevant to a potential participation in a clinical trial.