IL6 and bacterial infectious disease: Although the virus particles of SARS-CoV-2 infect host cells and can induce cytokine storms, IL-6 has also been used as a diagnostic and prognostic biomarker for severe bacterial infections.7 Similarly, we found that extremely high levels of IL-6 were strongly associated with the presence of septic shock or sepsis in COVID-19 patients (Fig. 1b).