IL6 and COVID-19: On day 1 of ICU admission, the average arterial oxygen saturation measured in our cohort of severe COVID-19 (n = 109), was (94 [79–98]%), PO2/FiO2 ratio was (150 ± 67 mmHg/20 ± 9 kPa), pH (7.4 ± 0.0), arterial PO2 (9.3 ± 1.7 kPa), arterial PCO2 (4.7 ± 0.9 kPa), lactate (1.2 ± 0.5 mmol/l), CRP (173 ± 82 mg/l) ferritin (2234 ± 4190 μg/l), IL-6 (135 ± 117 ng/l) and D-dimer (2.4 ± 4.0 ng/ml).