Inclusion Criteria:  1) Children hospitalized in the Pediatric department of the Hospices Civils de Lyon with PCR positive for a variant of the historical SARS-CoV2, 2) Adults hospitalized in the the Hospices Civils de Lyon, for a Covid-19 disease with documented infection by a variant of the SARS-CoV-2 and included in the NOSO-COR study with matching criteria described below.  Exclusion Criteria:  Any patient suspected of nosocomial infection. Any patient death during the Covid-19 infection. Any adult patient without children living home. Opposition to participate.