The COVID-19 pandemic revealed that immune protection differs across the body. While antibodies in the blood remain stable and protect against severe disease, mucosal immunity in the upper respiratory tract declines rapidly, allowing reinfection. In her TopBMemory project, Claudia Giesecke-Thiel investigates how the site of first pathogen contact shapes immune memory. Using pharyngeal tonsil organoids, her team aims to uncover mechanisms that could guide vaccines to induce lasting protection at mucosal barriers.