IL6 and COVID-19: Pre- and/or post-treatment WBC, neutrophil, and platelet counts, neutrophil-to-lymphocyte ratios, as well as CRP, ferritin, PCT, LDH, D-dimer, IL-6, and CTSS variably correlated with each other (p < 0.05), suggesting the panel of these biomarkers might be suitable to assess MIS and to monitor TCZ treatment effects on severe COVID-19-associated MIS (Table 3).