a study to evaluate the safety and efficacy of mrna-1345 vaccine targeting respiratory syncytial virus (rsv) in adults ≥60 years of age

Conditions: Respiratory Syncytial Virus

Summary: the main purpose of part a of this study is to evaluate the safety and tolerability of mrna-1345 vaccine and to demonstrate the efficacy of a single dose of mrna-1345 vaccine in the prevention of a first episode of rsv-associated lower respiratory tract disease (rsv-lrtd) as compared with placebo from 14 days postinjection through 12 months. the main purpose of part b of this study is to evaluate the safety, tolerability and immunogenicity of a booster dose (bd) of mrna-1345 administered 24 months after the primary dose.

the study will be conducted in 2 phases: phase 2 and phase 3. in the part a phase 2 segment, up to 2,000 participants will be randomly assigned to receive a single injection of either mrna-1345 vaccine at the selected dose or placebo in a 1:1 randomization ratio. in the part a phase 3 segment, approximately 35,000 participants will be randomly assigned to receive a single injection of either mrna-1345 vaccine at the selected dose or placebo in a 1:1 randomization ratio. in the part b substudy, 1500 participants who received a dose of mrna-1345 in part a phase 3 will be randomly assigned in a 2:1 randomization ratio to receive a single bd injection of either mrna-1345 at the selected dose or placebo.

Eligibility criteria:
key inclusion criteria (part a): * adults ≥ 60 years of age who are primarily responsible for self-care and activities of daily living. participants may have one or more chronic medical diagnoses (including chronic heart failure \[chf\] and chronic obstructive pulmonary disease \[copd\]), but should be medically stable * body mass index from ≥18 kilograms (kg)/square meter (m\^2) to ≤35 kg/m\^2 key inclusion criteria (part b): * randomized to and were subsequently vaccinated with the mrna-1345 study injection in part a at least 21 months prior to screening. key exclusion criteria (part a): * participation in another clinical research study where participant has received an investigational product (drug/biologic/device) within 6 months before the planned date of the day 1 study injection. * current participation in research involving receipt of any investigational rsv product * history of a serious reaction to any prior vaccination or guillain-barré syndrome within 6 weeks of any prior influenza immunization. * received or plans to receive any non-study vaccine within 28 days before or after the day 1 study injection. key exclusion criteria (part b): * participation in another clinical research study where participant has received an investigational product (drug/biologic/device) within 6 months before the planned date of bd study injection (bd day 1). * history of a serious reaction to any prior vaccination, or guillain-barré syndrome within 6 weeks of any prior influenza immunization. * received or plans to receive any non-study vaccine (including authorized or approved vaccines for the prevention of coronavirus disease 2019 (covid-19) regardless of type of vaccine) within 14 days before or after the bd day 1 study injection. * received or plans to receive any commercial rsv vaccination at any time prior to bd study injection (bd day 1) or during the substudy. other inclusion and/or exclusion criteria may apply.

Keywords: viral diseases messenger rna moderna mrna-1345 respiratory syncytial virus safety vaccines