The coronavirus disease 2019 (COVID-19) pandemic has drawn attention to new clinical and fundamental issues in the immunopathology of human diseases. Since in COVID-19 it is the ‘‘hyperimmune’’ response, called cytokine storm syndrome, which forms the basis of the pathogenesis of acute respiratory distress syndrome (ARDS) and multiorgan dysfunction in COVID-19, special attention is drawn to the possibility of “repurposing” (drug repurposing) of some widely used for treatment immune-mediated inflammatory rheumatic diseases (IMIRDs) anti-inflammatory drugs, including glucocorticoids (GC), disease-modified anti-rheumatic drugs (DMARDs), biologic agents and ‘‘targeted’’ DMARDs. In the spectrum of cytokines involved in the pathogenesis of cytokine storm syndrome in IMIRDs and COVID-19, great importance is attached to the pro-inflammatory cytokine, interleukin IL-6. The development and introduction into clinical practice of monoclonal antibodies (mAbs) that inhibit the activity of IL-6 are among the major advances in the treatment of IMIRDs, and in recent years, critical conditions within the framework of the cytokine storm syndrome, including in COVID-19. The review discusses the materials of numerous studies devoted to the problems of the efficacy and safety of mAbs to the IL-6 receptor (tocilizumab) and other mAbs that inhibit the activity of this cytokine in COVID-19. Despite the effectiveness of inhibiting IL-6 in patients with severe COVID-19, many theoretical and clinical problems of immunopathology and pharmacotherapy of this disease require further study.