inclusion criteria: ed patients positive to or suspected of covid-19 infection with at least one of the following symptoms: * fever * cough/dyspnea * respiratory symptoms or ed arrival for respiratory reason and for whom there are the following conditions: * spo2 \< 95% in ambient air or positive quick walk test * pao2/fio2 \> 200 in ambient air or with venturi mask, evaluated in 1 hour from ed arrival.

inclusion criteria: ed patients positive to or suspected of covid-19 infection with at least one of the following symptoms: * fever * cough/dyspnea * respiratory symptoms or ed arrival for respiratory reason and for whom there are the following conditions: * spo2 \< 95% in ambient air or positive quick walk test * pao2/fio2 \> 200 in ambient air or with venturi mask, evaluated in 1 hour from ed arrival.

inclusion criteria: ed patients positive to or suspected of covid-19 infection with at least one of the following symptoms: - fever - cough/dyspnea - respiratory symptoms or ed arrival for respiratory reason and for whom there are the following conditions: - spo2 < 95% in ambient air or positive quick walk test - pao2/fio2 > 200 in ambient air or with venturi mask, evaluated in 1 hour from ed arrival.

inclusion criteria: ed patients positive to or suspected of covid-19 infection with at least one of the following symptoms: - fever - cough/dyspnea - respiratory symptoms or ed arrival for respiratory reason and for whom there are the following conditions: - spo2 < 95% in ambient air or positive quick walk test - pao2/fio2 > 200 in ambient air or with venturi mask, evaluated in 1 hour from ed arrival.