CAT and COVID-19: The authors also mentioned that methylprednisolone treatment led to a rapid increase in antioxidant defense enzymes in erythrocytes (super oxide dismutase, SOD and catalase, CAT) resulting in clinical and echocardiographic improvement [21] which may additionally explain why sORP in severe COVID-19 patients (certainly intensively treated) significantly decreased in comparison to convalescent and healthy subjects.