A Study on the Immune Response and Safety of Vaccine Against Respiratory Syncytial Virus (RSV) Given to Adults 18 to 49 Years of Age at Increased Risk for Respiratory Syncytial Virus Disease, Compared to Older Adults 60 Years of Age and Above

Inclusion Criteria: * Participants and/or participant's parent(s)/ Legally acceptable representative (LAR) who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g., completion of the eDiary, attend study site visits, ability to access and utilize a phone or other electronic communications). * Written or witnessed informed consent obtained from the participant/participant's parent(s)/LAR(s) (participant must be able to understand the informed consent) prior to performance of any study-specific procedure. Written informed assent obtained from the participant (participant must be able to understand the informed assent) if he/she is less than the legal age prior to performance of any study-specific procedure. Specific inclusion criteria for all participants in Cohort 1 and Cohort 3 (RSV-A-AIR Group) • A male or female participant 18-49 YOA at the time of the study intervention administration. * Participants should be diagnosed with at least 1 of the following medical conditions if considered medically stable by the investigator: * Chronic cardiopulmonary disease resulting in activity restricting symptoms or use of long term medication: o Chronic obstructive pulmonary disease (COPD) o Asthma o Cystic fibrosis o Other chronic respiratory diseases: lung fibrosis, restrictive lung disease, interstitial lung disease, emphysema or bronchiectasis o Chronic heart failure: o Pre-existing Coronary Artery D…