ABSTRACT
The major causes of death of patients with COVID-19 include metabolic acidosis, septic shock, pulmonary edema, multiple organ failure and deep venous thrombosis. These systemic manifestations are associated with severe pathological damages of vital organs like lung and kidney that are caused by inflammatory storms. The occurrence, development and deterioration of disease is closely associated with the immune imbalance mechanisms such as disorder of lymphocyte subsets and emergence of cytokine storm. The cellular immunity plays a vital role. The expression levels of some blood inflammatory factors of the severe COVID-19 patients are remarkably elevated, IL-6 is a typical proinflammatory factor that causes the cytokine storm, which can be used for prediction of prognosis. IL-6 blockade may be an effective method to block the cytokine storm.