RAB11A and COVID-19: To this end, we made use of T cell lines from individual #521 who - up to the last evaluation time point in May 2024 and therefore three years after the first screening - had no history of COVID-19, had remained seronegative for antibodies against SARS-CoV-2 nucleocapsid and yet displayed strong CoV-YL8 responses by both fresh PBMCs and T cell lines.