In addition to well-known cytokines (e.g., IL-1, IL-6 and IL-10), chemokines, including CCL3, CXCL10, CXCL5, and CCR2, were found to have increased expression in peripheral blood mononuclear cells (PBMCs) derived from COVID-19 patients with moderate, severe and critical disease, and the levels of CCL3 and CXCL10 were also assessed in plasma. Here, CCL3 is linked to COVID-19.