IL6 and COVID-19: That is, patients with COVID-19 were immediately treated with adequate doses of IVIG [0.3–0.5 g/(kg ⋅ d) for 5 days] and low-molecular-weight heparin anticoagulation when the number of peripheral blood lymphocytes significantly reduced, the levels of inflammatory cytokines (such as interleukin 6) significantly increased, and coagulation D-dimer levels were four times higher than the upper limit of normal.