Rationale : The emergence of the novel, pathogenic SARS-coronavirus 2 (SARS-CoV-2) threatens public health. To date, there are no effective drug option to prevent the infection, nor therapeutics for controlling the deadly COVID-19. However, the majority of patients infected with SARS-Cov-2 eliminate the virus by mounting a protective antiviral immune response, associated in particular with the production of neutralizing antibodies. Neutralizing antibodies could be of particular interest for therapeutic purposes, but also for preventive applications, to protect people who have never been in contact with the virus, or immunocompromised patients.

The objectives of this study are :

• To generate human monoclonal antibodies neutralizing SARS-Cov-2 from immortalized B cells of convalescent patients.
• To compare the serological profiles between convalescent patients that develop mild or uncomplicated illness and convalescent patients that develop a more severe disease, that required hospitalization and oxygen support.
• To compare for each patient the neutralizing efficiency of plasma to the neutralizing capacities of the monoclonal antibodies generated with immortalized B cells.

Inclusion Criteria:

• Patient over 18 years old
• Patient who signed the study consent form
• Convalescent patient (at least 12 days after the onset of symptoms), having been sampled at Hospices Civils de Lyon for a suspected infection with SARS-Cov-2, confirmed by PCR.

Exclusion Criteria:

• Patient treated with rituximab
• Patient treated with immunoglobulins
• Patient over 18 years old, subject to a legal protection measure (guardianship or trusteeship)
• Patient deprived of liberty
• Pregnant or lactating woman
• Patient not affiliated to a social security scheme or beneficiary of a similar scheme.

This study relates to 10 adult subjects who were infected with SARS-Cov-2 (positivity confirmed by PCR test), who were symptomatic, and who were in the recovery phase when the blood sample was collected.

Among the 10 convalescent subjects who will be sampled, we will select two distinct populations:

(i) five convalescent patients (minimum 12 days after the onset of symptoms), diagnosed COVID + on the temporary sampling platform which was set up at HCL at the start of the epidemic, which notably concerns symptomatic healthcare professionals for whom hospitalization was not required; (ii) five convalescent patients (minimum 12 days after the onset of symptoms), hospitalized in the infectious diseases department of the Croix-Rousse hospital living in the metropolitan area of Lyon, having presented hypoxemic pneumonia requiring hospitalization.