ROC curve in Fig. 2B presents ferritin at 24 h (0.582; 95% CI 0.504–6.661), IL-6 (0.672; 95% CI 0.593–0.851), and LDH (0.608; 95% CI 0.527–0.6893), which were significant in predicting COVID-19 mortality. Here, IL6 is linked to COVID-19.