CCL4 and COVID-19: Moreover, samples of the bronchoalveolar lavage fluid (BALF) of patients with COVID-19 show the accumulation of various immune attractant chemokines, including C-C motif chemokine ligand (CCL)2, CCL3, CCL4, CCL7, CCL8, CCL20, CXCL6, and CXCL11 (4, 8, 9).