ALB and COVID-19: According to the results presented in the current article, it may be suggested that: (1) 3-Meleimido-PROXYL is a reliable reporter of conformational changes of albumin; (2) The nitroxide radical binds molecules whose thiol group is in a reduced state, so the doubly integrated spectrum of the radical is a measure of the amount of 3-Meleimido-PROXYL bound to redHSA; and (3) The obtained biophysical parameters correlate excellently with the severity and mortality in the studied patients and justify the application of SDSL-EPR spectroscopy in COVID-19 patients.