In a retrospective observational study, critically ill COVID-19 patients admitted to the ICU with the CoV-2 delta-variant between august 2021 and february 2022 were evaluated (ethics application nr. 129/22 of the ethics commssion of the university Ulm.

According to the recommendations, IgG seronegative SARSCoV2-Spike antibody (< 0,80 U/ml) COVID-19 patients were treated with 1 dose of subcutaneous casirivimab and imdevimab, 1200 mg (600 mg of each). Patients with CRP > 75 mg/l or IL-6 > 75 ng/l were treated with one dose of intravenous tocilizumab 8 mg/kg body weight. 28-day mortality and 30-day time course of leukocyte counts and serum concentrations of C-reactive protein (CRP), procalcitonin (PCT), interleukin 6 (IL-6) and ferritin in 4 patient groups, i. e., treated without (N) or with casirivimab / imdevimab (C) or tocilizumab (T), solely, or in combination of both (C + T), were evaluated.

Inclusion Criteria:

• Clinical diagnosis of COVID-19
• CoV-2 delta-variant
• critically ill patients
• ICU

Exclusion Criteria:

• tuberculosis
• active hepatitis
• HIV

In a retrospective observational study, critically ill COVID-19 patients admitted to the ICU with the CoV-2 delta-variant between august 2021 and february 2022 were evaluated. IgG seronegative SARSCoV2-Spike antibody (< 0,80 U/ml) COVID-19 patients were treated with 1 dose of subcutaneous casirivimab and imdevimab, 1200 mg (600 mg of each). Patients with CRP > 75 mg/l or IL-6 > 75 ng/l were treated with one dose of intravenous tocilizumab 8 mg/kg body weight.