CXCL9 and COVID-19: In order to extensively analyze the T cell response after COVID-19 vaccination we assessed on the same sample of QuantiFERON assay, the main chemokines produced in response to stimulation with Ag1 and Ag2 spike-derived peptides: MIG (CXCL9) and IP-10 (CXCL10), induced by IFN-γ; MCP-1 (CCL2) and IL-8 (CXCL8), namely monocyte-derived chemokines; and CCL5 (RANTES) as chemokine involved in an inflammatory response.