Saltsjobaden

Respiratory syncytial virus (RSV) commonly causes respiratory infections leading to hospitalizations, especially in infants and older adults. Arexvy is an approved vaccine designed to prevent RSV infection in people aged 60 and older, but there is limited information on how well it works in people aged 80 and above. This study aims to compare immune responses to the Arexvy vaccine between adults aged 80 years and older and those aged 60 to 65 years to better understand vaccine effectiveness in these groups. The study evaluates the immune response differences after vaccination with Arexvy, an adjuvanted RSV vaccine based on the prefusion-stabilized F protein and containing the AS01E adjuvant. Arexvy has shown efficacy against lower respiratory tract disease over three RSV seasons in adults 60 and older. This open-label phase IIIb trial focuses on comparing responses in the oldest and frail population versus younger elderly adults. Participants will receive a prime dose and revaccination with Arexvy. Participants will be assessed for immune responses and safety following vaccination. The study includes individuals living in the community or long-term care who are medically stable. Researchers will monitor health status, immune responses, and any side effects. The primary outcome will be measured at day 31 after vaccination. The study excludes those with prior RSV vaccination or certain medical conditions. Total participation duration and detailed follow-up procedures are based on the protocol requirements.