A Study of Various Respiratory Syncytial Virus (RSV) Pre-Fusion (preF)-Based Vaccine Formulations in Adults Aged 60 Years and Older

RSV is an important cause of serious respiratory infections in adults aged 60 years and older. The current study is divided into four cohorts, evaluating various doses and combinations of RSV preF-based vaccines. Cohort 1 will assess the safety and reactogenicity of different RSV preF-based vaccines. Cohort 2 is an expansion of cohort 1 and will assess both safety and immunogenicity of these different RSV vaccines. based on C1 and 2 data the optimal vaccine composition will be selected and further evaluated in Cohort 3 and 4 including durability and revaccination. Cohort 3 will accumulate safety data on the selected vaccine and optimize its formulation. Cohort 4 is an expansion of several arms in cohort 3, aimed to understand the durability of the immune response induced by the selected vaccine, and to explore the possibility for revaccination.