MPO and COVID-19: The potential effector targets were EGFR, CASP3, STAT3, ESR1, FPR2, F2, BCL2L1, BDKRB2, MPO, and ACE, through regulating signaling pathways, such as PI3K-Akt signaling pathway, MAPK signaling pathway, Jak-STAT signaling pathway, to suppress the inflammatory response, regulate the immune function, and reduce lung injury, thereby achieving the purpose of COVID-19 treatment.