How Routine Biomarkers and Blood Leucocytes Count Can Assist Diagnosis of COVID-19 in Emergency Department

December 2019 was the onset of an outbreak of an infection related to SARS-CoV-2, a new coronavirus detected in January 2020 and responsible for a disorder termed COVID-19. Since then, COVID-19 has spread worldwide and is responsible for an unprecedented pandemic with major threat on global health and social and economic stability. Covid-19 has a large spectrum of symptoms. Most patients experience mild or moderate flu-like disorder with cough, fever, and shortness of breath. More severe presentations may occur; patients sometimes develop an acute pneumonia that can lead to adult respiratory distress syndrome. A considerable number of publications have been released for the last 10 weeks to help physicians making diagnosis and treat patients. Chinese authors have extensively proposed description of the disease. As signs and symptoms are poorly specific, diagnosis mostly relies on detection of the virus by RT-PCR in the upper respiratory tract. Some uncommon images and localization are highly specific and sensitive on chest CT-scan, which is cornerstone for initial diagnosis. However, resources may lack during healthcare crisis and results of these investigations may be delayed or unavailable developper. Special attention should also be paid to usual laboratory analysis. Indeed, decreased lymphocytes and eosinophilic counts are frequently described as well as increase in D-dimers levels. Variation of C-reactive protein (CRP) and procalcitonin (PCT) have been reported. Coronavirus may have cardiac tropism and changes in cardiac biomarkers concentration may occur. Therefore, some data suggest that values of routine biomarkers and blood cell count may assist physicians at bedside to support diagnosis of COVID-19. To face the outbreak, organization of emergency departments (ED) was mandatory to separate patients flows and avoid mixing patients with COVID-19 and others. Most patients visiting EDs dedicated to initial COVID-19 management suffered of pneumonia-like sympto