The SARS-CoV-2 (COVID-19) infection is causing a global pandemic and a major health crisis in France.

Immunity is the body's ability to defend itself against infectious agents such as viruses. The progressive acquisition by a large part of the population of immunity to defend itself against the COVID-19 virus is one of the main mechanisms by which a resolution of this pandemic is hoped for. Recovery from infection and protection from the virus is likely to depend on the development of antibodies (proteins produced by the body to neutralize infectious agents) and T-cells (a type of white blood cell in the immune system) that can stop the virus from multiplying and killing it.

To date, the way and speed at which the T-lymphocytes active against the virus appear are not known. The development of biological tests to detect T-cells active against the virus in the blood of infected patients is therefore necessary.

In this context, we propose you to participate in a study that will study the immune system's response against the sars-CoV-2 virus during and after COVID-19 infection.

Inclusion Criteria:

• Patient with an acute SARS-CoV-2 infection, confirmed by PCR or typical CT images, requiring hospitalization in a COVID unit at the Rouen University Hospital (pneumonic form requiring oxygen therapy < 4 L/min.)
• Rouen University Hospital staff free of any symptomatology compatible with an SARS-CoV-2 infection (fever, cough, fatigue, loss of taste, loss of smell) since February 1, 2020
• Age ≥ 18 years old
• Adult patient who has read and understood the information letter and signed the consent form
• Affiliation to a social security scheme

Exclusion Criteria:

• Patient with PCR-confirmed SARS-CoV-2 infection and hospitalized in intensive care units (acute respiratory distress and/or organ failure, whose pathogenesis may differ from the more frequently described forms with secondary aggravation (5)).
• Patient with PCR-confirmed but non-hospitalized SARS-CoV-2 infection (non-acute form, managed by confinement)
• A person participating in a therapeutic trial that may interfere with the procedures being investigated, including lymphocyte response prior to D+56±14 days.
• Known Pregnancy
• Person deprived of liberty by an administrative or judicial decision or person placed under judicial protection / subtutorship or guardianship
• Staff at the Rouen University Hospital with SARS-CoV-2 infection confirmed by PCR and/or typical scan images during the epidemic period.
• Hospital staff who were exposed to the virus (working in a Covid unit)