The study purpose was to assess the outcomes of therapy with olokizumab within complex therapy of Coronavirus disease 2019 (COVID-19) in hospitalised patients in real clinical practice setting. The study investigated patients' characteristics, disease progression, and efficacy and safety of olokizumab therapy.

This was a multicentre retrospective cohort study of patients admitted to hospitals in various Russian Federation cities with positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid (RNA) laboratory test for the treatment of severe acute respiratory syndrome. The study used information from primary medical documentation of COVID-19 patients who had underwent diagnostic and therapeutic procedures in accordance with the hospital clinical practice. Clinical and laboratory data was collected and analysed to assess olokizumab safety, investigate other treatments, course and outcomes of the disease.

No additional tests or medical procedures were made as part of this study. If any data collected under the protocol was not available or not collected, they deemed lacking.

Based on the results of preliminary assessment of the number of records from the patients meeting inclusion / exclusion criteria in the clinical sites planning to participate in the project it was planned to include no more than 3000 patients in the study, of which about 1500 would be in the main group (received olokizumab therapy), and 1500 would be in the comparison group. It was planned to conduct an analysis in the general population (including taking into account its balancing using statistical methods, in case of significant differences in the initial characteristics of patients in groups), as well as in a subpopulation selected from pairs formed taking into account the comparability of patients by individual characteristics. In total, it was planned to form at least 200 pairs (or more, if the included population is highly comparable). Participation of several clinics in Russian Federation cities (not more than 10 cites) was expected to assure sufficient population for the study.

Data collection period for each hospitalised patient was equivalent to in-hospital period for the treatment of SARS-CoV-2 infection. Data collection by patients was made during hospital stay, including the day of discharge (treatment outcome or lethal outcome). The primary study variables were defined during 21-day observation period.

Inclusion Criteria:

• Confirmed diagnosis of SARS-CoV-2 (using virus ribonucleic acid polymerase chain reaction (RNA PCR) test).

• Hospital admission for COVID-19 therapy.

• Infiltrative lung changes based on imaging findings (chest X-ray, chest computed tomography (CT)).

• Indications for Preemptive anti-inflammatory therapy (PAT), including two or more signs below:

  • reduced oxygen saturation of the blood SpO2 ≤ 97 %
  • C-reactive protein (CRP) > 15 mg/L
  • body temperature > 37.5 °C for at least 3 days
  • white blood cell count < 4.0 x 10^9/L
  • absolute lymphocyte count < 2.0 x 10^9/L.

• Olokizumab therapy - for the test group.

• Source medical documents contain the information required for the study (lacking or incomplete data on some serum chemistry values are allowed: D-dimer, ferritin, IL-6, procalcitonin).

Exclusion Criteria:

• Inadequate information on patient's characteristics and therapy.
• Lack of documented confirmation of SARS-CoV-2 infection.
• Initiation of mechanical ventilation (MV) from the first day of admission in the control group or before olokizumab administration in the test group.
• Administration of systemic corticosteroids, IL-6, other immunosuppressants or immunoglobulins before hospital admission.
• Lack of indications to PAT
• Administration of olokizumab, other interleukin (IL) (interleukin-1 and interleukin-17) inhibitors and Janus-kinase inhibitors - for comparator group.

The study enrolls males and females aged ≥ 18 years with infection caused by SARS-CoV-2 who received in-hospital therapy. The study population includes all the patients admitted to hospital since June 2020, meeting inclusion / exclusion criteria with their data collected and analysed.