The SARS-CoV-2 identified in China in January 2020 is the cause of an unprecedented pandemic. The SARS-CoV-2 and each viral variant are responsible of a respiratory infectious disease, which can be asymptomatic. Nevertheless, a part of infected patients will experiment serious forms associated with a high mortality rate. Most serious forms present with lymphopenia and a functional exhaustion of speicifci T lymphocytes. Several studies showed that these quantitative and qualitative lymphocyte abnormalities are associated with unfavourable patients' outcome. The investigators hypothesized that the use of anti-viral T lymphocytes from convalescent COVID 19 donors could be helpful to improve the prognosis of COVID-19 serious forms. This study aims to demonstrate the feasibility of setting up a biobank that could allow the preservation and production of a cellular immunotherapy specific to SARS-CoV-2.