Another chemokine found to positively correlate with the RALE score was MCP-1/CCL2, which has chemoattractant properties for CCR2-expressing monocytes and macrophages (28), whereas no correlation was found between the RALE score and admission monocyte counts, MCP-1/CCL2 is associated with monocyte-derived macrophage infiltration in the lungs of patients with COVID-19 and is increased in those patients with acute respiratory distress syndrome in which it appears to play a key role in pulmonary fibrosis development (29). Here, CCL2 is linked to pulmonary fibrosis.