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 understood the briefing note and signed the informed consent form

Exclusion Criteria:

- Minor person

- Known Pregnancy

- Person deprived of liberty by an administrative or judicial decision or person
placed under judicial protection / subtutorship or guardianship

- Person not affiliated with social security

- Person who does not understand and speak French