COVID-19(28) SARS-CoV-2(28) Tocilizumab(16) Treatment(16) IL-6(16) Patient(16) COVID-19 patients(16) Cytokine storm(14) severe COVID-19(13) immune(13) clinical(12) therapy(12) occur(12) lead(11) cytokine(11) appear(10) expression(9) immunosenescence(9) Cytokine release syndrome(9) Immunotherapy(8) individual(8) humoral immune response(8) vaccination(8) severity(8) characterized(8) disease(8) dose(8) ARDS(7) Coronavirus disease 2019(7) IL-6 receptor(7)