IL6 and COVID-19: It was also found that the combination of d-dimer and IL-6 can be used to distinguish severe COVID-19 patients (area under the receiver operating characteristic [ROC] curve: 0.840) [39], suggesting that the high mortality rate of COVID-19 might be caused by the subsequent SIRS induced by a “cytokine storm.” It has been indicated that early interventions to attenuate this cytokine storm may improve the clinical outcomes of severe cases of COVID-19 [185].