EGF and COVID-19: We also observed a significant increase in the concentration of the monocyte chemoattractant protein-1 (MCP-1) and epidermal growth factor [EGF, which plays a key role in host response to coronaviruses and is implicated in lung disease induced by highly pathogenic respiratory viruses (49)] in young COVID-19 patients only whereas a trend towards high concentration of EGF was observed in aged patients (p=0.0848) (Supplementary Figure 1A).