Fig. 1.

Flow chart of selected patients.

1. Where validation by a biologist occured before or 20 days after recorded sample collection date and time. 2. Patients from Georges Pompidou European Hospital were excluded, as all biological and clinical data from this hospital were missing due to interoperability issues with the CDW. 3. Hospitalizations with no ICD-10 code for Covid-19, or with an ICD-10 code for Covid-19 and a first positive PCR sample obtained more than 10 days before or more than 3 days after admission. 4. Hospitalizations for Covid-19 with ICU transfer within 2 hours following hospital admission, and no visit in any other GPUH hospital in the preceding 24 hours