TNFRSF11B and COVID-19: Consistently, the RANKL/OPG ratio showed a good correlation also with the two inflammatory parameters that resulted significantly in this study to highlight the inflammatory response to COVID-19, namely IL-6 and sRAGE: IL- 6 as a systemic primary inflammatory cytokine involved in the cytokine storm resulting in COVID 19 disease, sRAGE as a predictive biomarker of COVID -19 severity.