A Study to Evaluate the Safety and Immunogenicity for Regimen Selection of Ad26.RSV.preF and/or RSV preF Protein Combinations Followed by Expanded Safety Evaluation in Adults Aged 60 Years and Older

Inclusion Criteria:

• 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
• In the investigator's clinical judgment, participant 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 symptoms and signs are medically controlled. If they are on medication for a condition, the medication dose must have been stable for at least 12 weeks preceding vaccination and expected to remain stable for the duration of the study. Participants will be included on the basis of physical examination, medical history, vital signs, and 12-lead electrocardiogram (ECG) performed at screening
• For participants in Cohorts 1 and 2 only: Participant must be healthy on the basis of clinical laboratory tests performed at screening. If the results of the laboratory screening tests are outside the central laboratory normal reference ranges and additionally within the limits of toxicity Grade 2 according to the United States (US) Food and Drug Administration (FDA) toxicity, the participant may be included only if the investigator judges the abnormalities or deviations from normal to be not clinically significant and appropriate and reasonable for the population under study. This determination must be recorded in the participant's source documents and initialed by the investigator
• From the time of each vaccination through 3 months after each vaccination, participant agrees not to donate blood
• Participant must be willing to provide verifiable identification, have means to be contacted and to contact the investigator during the study

Exclusion Criteria:

• Per serology testing in Cohorts 1 and 2 and per medical history in Cohort 3: Participant has chronic active hepatitis B or hepatitis C infection, documented by hepatitis B surface antigen and hepatitis C antibody, respectively
• Per serology testing in Cohorts 1 and 2 and per medical history in Cohort 3: Participant has human immunodeficiency virus (HIV) type 1 or type 2 infection
• Participant 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
• 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)
• Participant has received respiratory syncytial virus (RSV) vaccine in a previous RSV vaccine study at any time prior to randomization