Immunogenicity and Safety of the AS01E-adjuvanted Respiratory Syncytial Virus (RSV) Prefusion F Protein Vaccine in Adults Aged 18–49 Years at Increased Risk of RSV Disease Compared with Adults Aged ≥60 Years

Adjuvanted RSVPreF3 was immunologically noninferior in 18-49-year-olds with underlying conditions compared with ≥60-year-olds in whom efficacy was previously demonstrated, supporting efficacy inference in this younger population. Up to 6 months postvaccination, the vaccine elicited robust immune responses, and the safety profile was acceptable. Clinical Trial Registration: NCT06389487.