Definition of moderate and severe COVID-19 infection
All patients included in the present study had: i) A positive
nasopharyngeal swab for COVID-19, ii) thoracic CT findings compatible
with COVID-19 pneumonia and iii) hospitalized due to COVID-19 infection.
Patients fulfilling one or more of the following criteria were accepted
as severe COVID-19 infection: i) A respiratory rate >30
breaths/minute signifying respiratory distress, ii) a resting oxygen
saturation 93% or less, iii) ratio of partial arterial oxygen
saturation to the fraction of inspired oxygen <300 mmHg and
iv) respiratory failure or a critical life-threatening complication of
COVID-19 necessitating admission to intensive care unit. Patients who
did not fulfill these criteria were accepted as having a moderate
COVID-19 infection. Subjects within the control group had a negative
nasopharyngeal swab for COVID-19, with or without a negative CT scan for
COVID-19 pneumonia.