Systemic lupus erythematosus (SLE) is the most common chronic systemic autoimmune disorder, with 30000 patients followed in France. SLE patients are at increased risk of infections which are more frequent and severe both because of SLE disease itself and immunosuppressive drugs. A specific vaccination policy has been applied in such patients, in particular with pneumococcal vaccination. The vaccine response is however highly variable with > 50% of SLE patients who fail to reach immune protection after pneumococcal vaccination. In the current SARS Cov-2 pandemic context, vaccination using mRNA Covid-19 vaccine has started in France in January 2021. It is unclear whether and how SLE patients will develop protective and enduring immunity following SARS-CoV-2 vaccination. Major questions are indeed currently unanswered for patients with chronic autoimmune disease such as SLE who will receive mRNA Covid-19 vaccine: do they develop a humoral and cellular immune response comparable to the general population? How long will be the protective immune response in SLE patients? Can viral mRNA vaccine promote lupus flares? COVALUS project aims to study the humoral and cellular response following SARS Cov-2 vaccination in patients with systemic lupus erythematosus. Accurate knowledge of the immune response induced by Covid-19 vaccine in patients with autoimmune disease who receive immunosuppressive treatments will be essential for the epidemiological control of Covid-19 in this population.