A Study to Evaluate a Range of Dose Levels of an Adenovirus Serotype 26 (Ad26.RSV.preF)-Based Vaccine in Older Adults

A Randomized, Double-blind, Placebo-controlled Phase 2a Study to Evaluate a Range of Dose Levels of an Ad26.RSV.preF-based Vaccine in Adults Aged 60 Years and Older

The purpose of this study is to explore the dose-response relationship of immune responses induced by different dose levels of an Ad26.RSV.preF based vaccine (Cohort 1) and to assess the safety and reactogenicity of different dose levels of the Ad26.RSV.preF-based vaccine (Cohorts 2 and 3).

Inclusion Criteria:

• In the investigator's clinical judgment, participants must be either in good or stable health. Participants may have underlying illnesses such as hypertension, type 2 diabetes mellitus, hyperlipoproteinemia, or hypothyroidism, as long as their signs and symptoms are stable and medically controlled in the judgment of the investigator. Participants will be included on the basis of medical history and of physical examination and vital signs performed at screening (all cohorts), and of physical examination and/or vital signs performed prevaccination on Day 1 (Cohorts 2 and 3)
• A woman must be postmenopausal (defined as no menses for 12 months without an alternative medical cause) and not intending to conceive by any methods
• Agree to not donate blood from the time of vaccination until 3 months after vaccination
• Have a body mass index (BMI) less than (<) 40 kilogram per meter square (kg/m^2)
• Be willing to provide verifiable identification and have means to be contacted and to contact the investigator during the study

Exclusion Criteria:

• Has a contraindication to intramuscular injection (IM) injections and blood draws (example, bleeding disorders)
• 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)
• History of chronic urticaria (recurrent hives), eczema, or atopic dermatitis
• Has hepatitis B or C infection, including history of treated hepatitis C infection
• Received an active RSV vaccine in a previous RSV vaccine study or an Ad26-vectored vaccine at any time prior to randomization