In stages characterized by hypoxemia (IIb and III), IL-6 levels did correlate with patient's respiratory failure severity, as we observed a significant negative correlation with SpO2 (r = −0.324, p = 0.0075) and a significant negative correlation with PaO2 (r = −0.335, p = 0.0026) (Figures 2A,B). This evidence concerns the gene IL6 and respiratory failure.