IL6 and COVID-19: Many studies have used various biomarkers, such as CRP [39–44], PCT [39, 43, 45, 46], IL-6 [39, 43, 46], WBC [40, 47–49], D-dimer [42, 44, 46, 50, 51], lactate dehydrogenase (LDH) [39, 42–44, 46, 47], N-terminal pro-B-type natriuretic peptide (NT-proBNP) [39, 52, 53], and Troponin T [39, 54], and critical illness scores, such as APACHE II [55–57], SOFA [55, 56, 58–60], SAPS [61–64], and CURB65 [59, 61, 65], to evaluate the prognosis of patients with COVID-19.