* sever covid-19 infection patients * sars-cov-2 specific antibodies (including igm and igg) were positive before included * cardiac function grade iii or iv, or left ventricular ejection fraction \< 30% * history of known or suspected active pulmonary tuberculosis or extra-pulmonary tuberculosis * chronic renal failure needs maintenance dialysis * history of solid malignant/tumor or hematological malignancy * pregnancy or lactation

* sever covid-19 infection patients * sars-cov-2 specific antibodies (including igm and igg) were positive before included * cardiac function grade iii or iv, or left ventricular ejection fraction \< 30% * history of known or suspected active pulmonary tuberculosis or extra-pulmonary tuberculosis * chronic renal failure needs maintenance dialysis * history of solid malignant/tumor or hematological malignancy * pregnancy or lactation

- sever covid-19 infection patients - sars-cov-2 specific antibodies (including igm and igg) were positive before included - cardiac function grade iii or iv, or left ventricular ejection fraction < 30% - history of known or suspected active pulmonary tuberculosis or extra-pulmonary tuberculosis - chronic renal failure needs maintenance dialysis - history of solid malignant/tumor or hematological malignancy - pregnancy or lactation

- sever covid-19 infection patients - sars-cov-2 specific antibodies (including igm and igg) were positive before included - cardiac function grade iii or iv, or left ventricular ejection fraction < 30% - history of known or suspected active pulmonary tuberculosis or extra-pulmonary tuberculosis - chronic renal failure needs maintenance dialysis - history of solid malignant/tumor or hematological malignancy - pregnancy or lactation