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).