In January 2020, researchers isolated and sequenced in China from patients with severe atypical pneumonia a novel coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has rapidly spread throughout the world. SARS-CoV-2 may trigger hyperstimulation of immune system with an autoinflammatory response but also the development of an autoimmune process. These autoimmune responses may also develop through the molecular mimicry between virus and human-self components. Multiple autoantibodies have been described in COVID-19 patients.

Annexin A2 (ANXA2), an endothelial cell receptor for plasminogen and tissue plasminogen activator has been identified as a new autoantigen in antiphospholipid syndrome. ANXA2 has been identified as candidate autoantigen recognized by SARS patient sera. ANXA2 contributes also to pulmonary microvascular integrity. These data lead to identify anti-ANXA2 antibodies in COVID-19 patient sera and to know if the presence of these antibodies is associated with pulmonary injury or thrombosis in COVID-19 and represents a marker of severity.

Inclusion Criteria:

• 18 years and older
• All patients hospitalized in Amiens University Hospital with COVID-19 infection

Exclusion Criteria:

• Autoimmune diseases
• Chronic viral infection by hepatitis B virus, hepatitis C virus or human immunodeficiency virus (HIV)
• Immunosuppressive treatment
• Solid tumors
• Hematological malignancies

All patients hospitalized in Amiens University Hospital with COVID-19 infection