Severity of the New UK SARS-Cov2 Variant in COVID-19 Infection

The COVID-19 epidemic has now raged for more than a year with more than 100 million identified cases and nearly 2.5 million deaths worldwide. Since November 2020, we have been witnessing the emergence of viral variants in different regions of the world. This expected genetic drift of the virus, but somewhat abrupt since November, raises questions concerning the characteristics of transmissibility, pathogenicity, sensitivity to possible treatments, and escape from natural or vaccine immunity. The objective of this study is to find out whether the new variants of SARS-CoV-2 are associated with particular clinical forms. The results of this research will provide elements to determine whether the new variants of SARS-CoV-2 are associated with more severe clinical forms.

SEVASAR is a paired cohort study with retrospective data collection: * Presentation: patients hospitalized for COVID-19 with SARS-CoV-2 variant 20I / 501Y.V1 * Not exposed: patients hospitalized for COVID-19 with SARS-CoV-2 corresponding to wild variants type 20A. EU1 or 20A. EU2 The severity of illness will be compared between pairs. Disease severity will be assessed according to the following definition: defined by a composite criterion including, at 28 days after hospital admission: WHO scale \>5 /11 levels, (death OR need for invasive ventilation OR need for high flow ventilation (Optiflex or NIV or CPAP) or high concentration mask. This event will be taken into account regardless of its time of occurrence between the first day of the hospitalization studied and D29 after hospital admission.