Fig. 1

IL-6 concentration in the sera of COVID-19 patients a) Mean of IL-6 levels in the three groups of COVID-19 patients. b The values are significantly higher in the group of critically and severely ill patients than in moderately ill patients. c) ROC curves of IL-6 predictive value for the severity of COVID-19. The asterisks indicate statistically significant differences among the groups (p < 0.05) (*) using Mann Whitney test. ROC: receiver operator characteristic; AUC: area under curve