COVID19 Ag- The COVID19 antigen test can directly detect whether the human sample contains the COVID19. The diagnosis is fast, accurate, and requires low equipment and personnel.It can be used for early screening and early diagnosis, suitable for large- scale screening in primary hospitals, and results can be obtained within 15 minutes as soon as possible. COVID19 NAb- Clinically used in the auxiliary evaluation of the effect of the COVID19 vaccine and evaluation of neutralization antibodies in recovered patients after infection. Ferritin- Serum ferritin levels are found to be closely related to the severity of COVID- 19. D-Dimer- D-Dimer increases significantly in most severe COVID-19 patients, with frequently clotting disorders and microthrombotic formation in perioheral blood vessels. Severe patients with new coronary pneumonia can quickly develop into acute respiratory distress syndrome, septic shock, difficult to correct metabolic acidosis, coagulopathy, and multiple organ failure. D-dimer is elevated in patients with severe pneumonia. CRP- CRP level increases in most COVID-19 patients.Most patients with new coronary pneumonia have elevated C- reactive protein (CRP) and erythrocyte sedimentation rate, and normal procalcitonin; severe and critical patients often have elevated inflammatory factors. IL-6- The elevation of IL- 6 is significantly related to the clinical manifestations of patients with severe COVID-19. The decrease of IL- 6 is closely related to the effectiveness of treatment.and the increase of IL- 6 indicates aggravation of the disease. PCT- PCT level stavs normal in COVID-19 patients, but increases when there is bateria infection. PCT is more sensitive to the diagnosis and identification of systemic bacterial infections, treatment effects and prognosis than C- reactive protein (CRP) and various inflammatory response factors (bacterial endotoxin, TNF-α, IL-2), and is more clinically practical value. SAA- SAA has played a certain role in the early diagnosis of COVID19, the classification of the severity of infection, the progression of the disease, and the evaluation of outcome. In patients with new coronary pneumonia, the serum SAA level will increase significantly, anc the more severe the disease, the greater the increase in SAA.