SIRPA and COVID-19: CD47 interacts with signal regulatory protein α (SIRP α) to transmit an anti-phagocytic “don’t eat me” signal to mediate immune escape.63 The CD47 gene is up-regulated in human bronchial epithelial A549 lung cancer cells, Caco2 colorectal carcinoma cells, and Calu-3 lung cancer cells infected with SARS-CoV-2 accompanied by an increase in SIRPα in monocyte infected cells.64 It was found that CD47 may be related to COVID-19 pulmonary fibrosis, which can be reversed by an anti-CD47 antibody in a mouse model study.65,66