Systematic Offer of Nurse-Driven Screening for COVID-19 in Emergency Departments in the Paris Metropolitan Area, DEPIST-COVID

European countries faced another wave of the SARS-CoV2 pandemic, which has led to a lockdown in France in November 2020 in order to avoid overwhelming health services. To prevent or reduce another wave, the strategy calls for vaccination, maintaining barrier measures and testing and isolating infected persons in order to break the cycles of infection. The latter objective is made difficult by the existence of asymptomatic carriers or symptomatic carriers that have very few symptoms and that aren't tested. Identification of these carriers in the general population is usually based on a search for close contact persons from those who were tested positive or from identified clusters. Experiments of mass testing are being carried out or were carried out, for example in Liverpool or Slovakia but, in order for them to be effective, they must be repeated, which limits feasibility. Another strategy of wide screening in the general population to identify asymptomatic persons is to offer a systematic screening during medical consultations and particularly in the emergency departments (ED). This strategy grants access to the entire population attending health facilities, including persons with lower income. This strategy can be conducted continuously in order to: 1) contribute to controlling the epidemic by identifying and isolating asymptomatic persons and their close contacts; 2) provide an observatory on the evolution of viral circulation in the general population. To the best of the knowledge, this strategy has not been evaluated and will be tested it in 18 emergency departments in the Paris Metropolitan area (Ile-de-France), one of the most SARS-CoV2 affected regions. The primary objective is to evaluate the benefit of a systematic offer of nurse-driven SARS-Cov2 screening by rapid testing (molecular multiplex PCR/ RT-LAMP) to identify infected persons, associated with the usual practice of the EDs (intervention strategy) compared to a period based on usual practice of the EDs (control strategy). The primary outcome is the proportion of patients tested positive for SARS-CoV2 amongst the flow of consulting adults. The secondary outcomes are to: * compare the proportion of patients tested positive for SARS-CoV2 amongst asymptomatic patients tested in the Paris Metropolitan area at the same period (the comparison will also be done amongst the geographical area of each ED, amongst symptomatic patients tested and also amongst the entire tested population) * evaluate the feasibility of the screening strategy * describe the patients tested for SARS-Cov2 in both periods : * proportion of positive tests * proportion of asymptomatic patients amongst tested patients and amongst SARS-Cov2 positive patients * For the symptomatic patients tested positive : symptomology * Patient exposure factors with the DEPIST-COVID questionnaire and according to SARS-Cov2 test result. * describe socio-demographic and behavioral factors and habits associated with SARS-Cov2 infection in patients tested in one of the following schemes: DEPIST-COVID, ComCor (Pasteur Institute) and COVISAN. * estimate the incidence of new SARS-Cov2 infections in the Paris Metropolitan area: proportion of positive patients and their profiles. To estimate the under-detection of cases in the region, and compare with results from the model experiment. * estimate the number of close contact persons who have been tested for SARS-Cov2, who have been tested positive and who have been isolated over both periods. Methods The strategies will be compared during two periods in 18 EDS of Paris metropolitan area following a cluster-randomized two-period crossover design. Each period will last 1 month. Patients will participate to a follow-up call (within 15 days ±10). The periods will be separated by an expected period of washout of a minimum of 1 day . During intervention periods, nurses will suggest performing a SARS-CoV2 test to patients. According to the answers to a self-administered questionnaire, a PCR multiplex will be performed for symptomatic patients and a RT-LAMP for asymptomatic patients.