inclusion criteria: 1. aged 18-75 years old 2. awake non-intubated spontaneously breathing patients 3. confirmed diagnosis of severe covid-19; manifesting as dyspnea with respiratory rate ≥ 30 breaths/min, pulse rate ≥ 100 beats/min, oxygen saturation ≤93%, or partial pressure of arterial oxygen (pao2) to fraction of inspired oxygen (fio2) ratio ≤ 150 mmhg. 4. positive rt-pcr for sars-cov-2 from analysis of nasopharyngeal, oropharyngeal swab, or tracheal secretion specimens and with chest x-ray showing bilateral infiltrations or chest computerized tomographic (ct) images showing exudation or consolidation. 5. requiring supplemental oxygen (nasal cannula, non-invasive cpap, non-rebreathing face mask) 6. capable of adopting a prone posture independently.

inclusion criteria: 1. aged 18-75 years old 2. awake non-intubated spontaneously breathing patients 3. confirmed diagnosis of severe covid-19; manifesting as dyspnea with respiratory rate ≥ 30 breaths/min, pulse rate ≥ 100 beats/min, oxygen saturation ≤93%, or partial pressure of arterial oxygen (pao2) to fraction of inspired oxygen (fio2) ratio ≤ 150 mmhg. 4. positive rt-pcr for sars-cov-2 from analysis of nasopharyngeal, oropharyngeal swab, or tracheal secretion specimens and with chest x-ray showing bilateral infiltrations or chest computerized tomographic (ct) images showing exudation or consolidation. 5. requiring supplemental oxygen (nasal cannula, non-invasive cpap, non-rebreathing face mask) 6. capable of adopting a prone posture independently.

inclusion criteria: aged 18-75 years old awake non-intubated spontaneously breathing patients confirmed diagnosis of severe covid-19; manifesting as dyspnea with respiratory rate ≥ 30 breaths/min, pulse rate ≥ 100 beats/min, oxygen saturation ≤93%, or partial pressure of arterial oxygen (pao2) to fraction of inspired oxygen (fio2) ratio ≤ 150 mmhg. positive rt-pcr for sars-cov-2 from analysis of nasopharyngeal, oropharyngeal swab, or tracheal secretion specimens and with chest x-ray showing bilateral infiltrations or chest computerized tomographic (ct) images showing exudation or consolidation. requiring supplemental oxygen (nasal cannula, non-invasive cpap, non-rebreathing face mask) capable of adopting a prone posture independently.

inclusion criteria: aged 18-75 years old awake non-intubated spontaneously breathing patients confirmed diagnosis of severe covid-19; manifesting as dyspnea with respiratory rate ≥ 30 breaths/min, pulse rate ≥ 100 beats/min, oxygen saturation ≤93%, or partial pressure of arterial oxygen (pao2) to fraction of inspired oxygen (fio2) ratio ≤ 150 mmhg. positive rt-pcr for sars-cov-2 from analysis of nasopharyngeal, oropharyngeal swab, or tracheal secretion specimens and with chest x-ray showing bilateral infiltrations or chest computerized tomographic (ct) images showing exudation or consolidation. requiring supplemental oxygen (nasal cannula, non-invasive cpap, non-rebreathing face mask) capable of adopting a prone posture independently.

inclusion criteria: 1. aged 18-75 years old 2. awake non-intubated spontaneously breathing patients 3. confirmed diagnosis of severe covid-19; manifesting as dyspnea with respiratory rate ≥ 30 breaths/min, pulse rate ≥ 100 beats/min, oxygen saturation ≤93%, or partial pressure of arterial oxygen (pao2) to fraction of inspired oxygen (fio2) ratio ≤ 150 mmhg. 4. positive rt-pcr for sars-cov-2 from analysis of nasopharyngeal, oropharyngeal swab, or tracheal secretion specimens and with chest x-ray showing bilateral infiltrations or chest computerized tomographic (ct) images showing exudation or consolidation. 5. requiring supplemental oxygen (nasal cannula, non-invasive cpap, non-rebreathing face mask) 6. capable of adopting a prone posture independently.

inclusion criteria: 1. aged 18-75 years old 2. awake non-intubated spontaneously breathing patients 3. confirmed diagnosis of severe covid-19; manifesting as dyspnea with respiratory rate ≥ 30 breaths/min, pulse rate ≥ 100 beats/min, oxygen saturation ≤93%, or partial pressure of arterial oxygen (pao2) to fraction of inspired oxygen (fio2) ratio ≤ 150 mmhg. 4. positive rt-pcr for sars-cov-2 from analysis of nasopharyngeal, oropharyngeal swab, or tracheal secretion specimens and with chest x-ray showing bilateral infiltrations or chest computerized tomographic (ct) images showing exudation or consolidation. 5. requiring supplemental oxygen (nasal cannula, non-invasive cpap, non-rebreathing face mask) 6. capable of adopting a prone posture independently.