The current pandemic caused by the newly identified coronavirus responsible for COVID-19 is a major threat to our populations and societies.

Hypothesis/Objective The acquisition of protective immunity at the level of the individual, either through vaccination or natural resolution of the infection, progressively leads at the level of the population to the reduction of the fraction of the population that can be productively infected and transmit the virus, hence, leading to the diminution of the rate of transmission, a phenomenon called herd immunity. Herd immunity was proposed as a strategy to control the infection. However, it remains difficult to model group immunity given the limited knowledge of the interaction between the host immune system with the virus, whose capacity to evolve in face of a neutralizing response is also not known. It is therefore important to acquire a better knowledge of the immunological memory that ensures the resolution of COVID-19 after SARS-CoV2 infection.

Method To study single-cell B and T memory cells specific for the anti-SARS-CoV-2 response and characterize somatic mutations of immunoglobulin genes and TCR, in hospitalized and symptomatic patients and in patients cured of SARS-CoV-2.

Inclusion Criteria:

• Patients who have recovered from CoV-2-SARS
• Adult patient (≥ 18 years old) with a positive SARS-CoV-2 PCR.
• Adult patient (≥ 18 years old) who has recovered from SARS-CoV-2 i.e. has been free of clinical symptoms for more than 15 days and has not been hospitalized and for less than 6 weeks.
• Patient affiliated to a social security scheme.

Patients hospitalized for SARS-CoV-2

• Adult patient (≥ 18 years old) with a positive SARS-CoV-2 PCR.
• Adult patient (≥ 18 years old) with clinical symptoms for more than 3 days and hospitalized.

Exclusion Criteria:

• Refusal of the patient to participate in the study.
• Patient under guardianship / curatorship

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