On the other hand, secretion of mucin-1 (muc1) and surfactant protein D (sftp-D) are important defense mechanisms in the lungs against pathogenic infection, while elevated plasminogen activator inhibitor-I (PAI-1) is a risk factor for thrombosis and has been shown to be correlated with COVID-19 severity (30). The gene discussed is SERPINE1; the disease is infection.