A Study Evaluating the Immunogenicity of Different Clinical Trial Materials of Ad26.RSV.preF- Based Vaccine in Adults Aged 60 - 75 Years Old

A Randomized, Double-blind Phase 3 Study to Compare the Immunogenicity of Clinical Trial Material of an Ad26.RSV.preF-based Vaccine for Phase 3 With Clinical Trial Material Representative of Phase 2b in Adults Aged 60 to 75 Years

The purpose of this study is to demonstrate non-inferiority in terms of humoral immune responses induced by vaccination with one dose of the Phase 3 clinical trial material (CTM) compared with one dose of the Phase 2b CTM.

Inclusion Criteria:

• Willing and able to adhere to the prohibitions and restrictions specified in the protocol
• 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
• In the investigator's clinical judgment, participant must be in stable health at the time of vaccination. Participants may have underlying illnesses such as hypertension, congestive heart failure, chronic obstructive pulmonary disease, type 2 diabetes, hyperlipoproteinemia, or hypothyroidism, 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. Participants will be included on the basis of medical history, and vital signs performed between informed consent form (ICF) signature and vaccination
• Must be willing to provide verifiable identification, has means to be contacted and to contact the investigator during the study
• From the time of vaccination through 3 months after vaccination, agrees not to donate blood

Exclusion Criteria:

• Known or suspected allergy or history of anaphylaxis or other serious adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine)
• Abnormal function of the immune system resulting from clinical condition or medication
• History of acute polyneuropathy (example, Guillain-Barré syndrome) or chronic idiopathic demyelinating polyneuropathy
• History of thrombosis with thrombocytopenia syndrome (TTS) or heparin-induced thrombocytopenia and thrombosis (HITT)
• Has had major surgery (per the investigator's judgment) within 4 weeks before administration of the study vaccine or will not have recovered from surgery per the investigator's judgment at time of vaccination