A Study of an Ad26.RSV.preF-based Regimen in the Prevention of Reverse Transcriptase Polymerase Chain Reaction (RT-PCR)-Confirmed Respiratory Syncytial Virus (RSV)-Mediated Lower Respiratory Tract Disease in Adults Aged 65 Years and Older

A Randomized, Double-blind, Placebo-controlled Phase 2b Study to Assess the Efficacy, Immunogenicity and Safety of an Ad26.RSV.preF-based Regimen in the Prevention of RT PCR-confirmed RSV-mediated Lower Respiratory Tract Disease in Adults Aged 65 Years and Older

The purpose of this study is to demonstrate the efficacy of active study vaccine in the prevention of reverse transcriptase polymerase chain reaction (RT-PCR) confirmed respiratory syncytial virus (RSV)-mediated lower respiratory tract disease (LRTD), when compared to placebo.

Inclusion Criteria:

• Participant must have a body mass index (BMI) less than (<)40 kilogram per meter square (kg/m^2)
• Before randomization, a woman 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
• Participant must be either in good or stable health. Participants may have mild to moderate underlying illnesses such as chronic cardiac diseases and chronic lung disease (asthma and chronic obstructive pulmonary disease [COPD]), congestive heart failure (CHF), hypertension, type 2 diabetes mellitus, hyperlipoproteinemia, or hypothyroidism, as long as their symptoms and signs are stable and medically controlled in the judgment of the investigator. Participants will be included on the basis of physical examination, medical history, and vital signs performed between informed consent form (ICF) signature and vaccination on Day 1
• From the time of vaccination through 3 months after vaccination, participant agrees not to donate blood
• Participant must be able to read, understand, and complete questionnaires in the eDiary (or a paper safety diary, if designated by the sponsor)
• Participant must be willing to provide verifiable identification, have means to be contacted and to contact the investigator during the study

Exclusion Criteria:

• Participant has an acute illness (including acute respiratory illnesses) or body temperature greater than or equal to (>=)38.0 degree Celsius (ºC) within 24 hours prior to administration of study vaccine. In such a situation, enrollment at a later date is permitted
• Participant has a severe or potentially life-threatening chronic disorder such as severe chronic cardiac diseases and severe chronic lung disease (asthma and COPD), advanced CHF, end-stage renal disease with or without dialysis, clinically unstable cardiac disease, Alzheimer's disease, or has any 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, limit, or confound the protocol-specified assessments
• Participant has a history of malignancy within 5 years before screening (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix, or malignancy, which is considered cured with minimal risk of recurrence)
• Per medical history, participant has chronic active hepatitis B or hepatitis C infection
• Per medical history, participant has human immunodeficiency virus (HIV) type 1 or type 2 infection
• Participant has a known allergy, or history of anaphylaxis or other serious adverse reactions to vaccines or vaccine components (including any of the constituents of the study vaccine)