The aim of this study is to investigate whether baricitinib is non-inferior to tocilizumab in severe COVID-19.

Patients with COVID-19 will be assigned to one of the two arms on 1:1 ratio based on the time point that PaO2/FiO2<200 will be observed. Patients aged 18 years or older with PaO2/FiO2 <200 at any time during their hospitalization will be included in the analysis irrespective of values in inflammatory markers, such as CRP and ferritin. Exclusion criteria will be: age<18 years, pregnancy, glomerular filtration rate<30 and application of mechanical ventilation prior patients' transfer to our Hospital. Each patient or the patient's legally authorized representative provided written or witnessed oral informed consent.

Day 1 will be considered the first day that PaO2/FiO2<200 will be identified. Treatment with either tocilizumab or baricitinib will start from day 1. Primary and secondary outcomes will be assessed in the days described below.

This study aims to investigate whether baricitinib is non-inferior to tocilizumab in patients with severe COVID-19. Two hundred fifty one (n=251) patients will be enrolled based on the following assumptions: 1) HR θ 1, 2) HR θο 1.5, 3) overall probability of event (primary end point) 0.6 (based on previous records of our hospital), 4) power 80%, 5) type I error α 5%.

Inclusion Criteria:

- COVID-19, PaO2/FiO2<200

Exclusion Criteria:

- Age<18 years, Pregnancy, Glomerular filtration rate<30, Application of mechanical ventilation prior patients' transfer to our Hospital

data will be available upon request