Evaluation of Serological Techniques for Screening for COVID-19 Infection at the University Hospital of Rouen

Inclusion Criteria: The inclusion criteria in the retrospective "Negative/Potentially Interfering" group are as follows : * Adult patient sampled prior to the onset of the COVID-19 epidemic (before January 2020) * Patient presenting a coronavirus infection other than SARS-CoV-2, or other respiratory viral infections (influenza, metapneumovirus) * Patients for whom a serum is kept in the biocollection declared under the number AC-2014-2293 and kept in the Institute of Clinical Biology, University Hospital of Rouen. The criteria for inclusion in the "acute point infection" group are as follows: * Patients screened by a positive RT-PCR for an SARS-CoV-2 infection * Patients aged ≥ 18 years old * Patients taken in charge in the emergency room / in a unit / in COVID resuscitation at the Rouen University Hospital. * Patients having read and understood the briefing note * Non-opposition to participation in the study The criteria for inclusion in the "Sequential acute infection" group are as follows: * Patients with positive RT-PCR for CoV-2-SARS infection * Patients aged ≥ 18 years old * Taken care of in a COVID unit at the Rouen University Hospital * Having read and understood the briefing note and signed the informed consent form The criteria for inclusion in the "Convalescent" group are as follows: * Caregivers working at the UH of Rouen * Screened by positive RT-PCR for SARS-CoV-2 infection, * Healed for at least one month at the time of inclusion * Having read and under…