Phase 2b Study Evaluating One Versus Two Doses of the Adjuvanted Arexvy RSV Vaccine in Adults 18 and Older With Weakened Immune Systems

What this Trial Is About

Respiratory syncytial virus RSV causes respiratory infections worldwide, often peaking in autumn and winter in temperate zones. Immunocompromised patients, such as those with underlying respiratory, cardiovascular, endocrinological diseases or after hematologic stem cell transplantation HSCT, face increased risk of severe RSV infections requiring intensive care, with high mortality rates. This study aims to evaluate if immunocompromised patients benefit from receiving two doses of the adjuvanted RSV vaccine Arexvy compared to one dose, to better inform vaccine recommendations. Participants in this randomized, phase 2b study are divided into groups based on their health conditions. Groups 1 to 3, consisting of immunocompromised patients with hemato-oncological diseases, lung cancer, or autoimmunechronic inflammatory diseases, will receive two doses of Arexvy about 1 to 2 months apart. Group 4, made up of healthy elderly individuals aged 60 and older, will receive either one dose of Arexvy and one placebo dose. The additional dose for immunocompromised groups is administered off-label. Throughout the study, researchers will measure the immune responses by assessing neutralizing antibodies against RSV-A and RSV-B after each vaccine dose, along with monitoring safety. Participants will be followed for up to 14 months to evaluate the immune response increase after the second dose compared to the first. The study includes evaluation of both humoral and cellular immunity and will help guide future vaccination strategies for immunocompromised patients.

RSV Vaccination in Immunocompromised Patients.