A Study of Adenovirus Serotype 26.Respiratory Syncytial Virus.Pre-Fusion F (Ad26.RSV.preF)-Based Vaccine for Prevention of Respiratory Syncytial Virus (RSV) Mediated- Lower Respiratory Tract Disease (LRTD) in Japanese Participants

A Randomized, Double-blind, Placebo-controlled Phase 3 Study to Evaluate Efficacy, Safety, Reactogenicity, and Immunogenicity of an Ad26.RSV.preF-based Vaccine in Japanese Adults Aged 60 Years and Older, and Safety, Reactogenicity, and Immunogenicity of the Vaccine in Japanese Adults Aged 20 to 59 Years at High-risk of RSV Disease

The purpose of the study is to evaluate the efficacy of study vaccine in the prevention of Reverse Transcriptase Polymerase Chain Reaction (RT-PCR)-confirmed RSV mediated- lower Respiratory Tract Disease (LRTD) over one RSV season when compared to placebo in adults aged 60 years and above and to demonstrate the non-inferiority of the vaccine in high-risk adults aged 20 to 59 years versus in adults aged 60 years and older in terms of humoral immune response.

Inclusion Criteria:

For Participants in Cohort 1 only

• Must be greater than or equal to (>=60) years old on the day of signing the informed consent form (ICF) and expected to be available for the duration of the study
• Before randomization, a participant must be postmenopausal (postmenopausal state is defined as no menses for 12 months without an alternative medical cause); and not intending to conceive by any methods
• Participants may have underlying illnesses such as hypertension, congestive heart failure (CHF), Chronic obstructive pulmonary disease (COPD), type 2 diabetes, hyperlipoproteinemia, or hypothyroidism, as long as their symptoms and signs are stable and medically controlled in the judgement of the investigator at the time of vaccination, and these conditions receive routine follow-up by the participant's healthcare provider

For Participants in Cohort 2 only

• Must be aged 20 to 59 years (inclusive) on the day of signing the ICF and expected to be available for the duration of the study
• Has an existing chronic heart or lung condition, without hospitalizations or major medication class change (that is, new or stopped medications) within 30 days prior to screening
• Participant may have other underlying illnesses as long as their symptoms and signs are stable at the time of vaccination, and these conditions receive routine follow-up by the participant's healthcare provider

Exclusion Criteria:

• Has a serious clinically unstable condition like, (example, end-stage renal disease with or without dialysis, clinically unstable cardiac disease), Alzheimer's disease, or any other condition for which, in the opinion of the investigator, participation would not be in the best interest of the participant (example, compromise well-being) or that could prevent or limit the protocol-specified assessments
• History of malignancy within 5 years before screening or revaccination not in the following categories: a. participants with squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix may be enrolled at the discretion of the investigator; b. participants with a history of malignancy within 5 years, which is considered cured with minimal risk of recurrence per investigator's judgement, can be enrolled
• Had major surgery (example, major cardiopulmonary or abdominal operations) as per the investigator's judgment within 4 weeks before vaccination, or will not have fully recovered from surgery, or has major surgery planned during the time the participant is expected to participate in the study
• Has an acute illness (including acute respiratory illnesses) or body temperature of >=38.0 degree Celsius (ºC) (>=100.4 Fahrenheit [ºF ] within 24 hours prior to administration of study vaccine)
• Has had major psychiatric illness and/or drug or alcohol abuse which in the investigator's opinion would compromise the participant's safety and/or compliance with the study procedures