STAT3 and COVID-19: Serum miR-155 regulates inflammation by targeting repressor of cytokine signaling 1 (SOCS1) and inhibiting Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway 67, indicating that circulating miR-155 may play a crucial role in the pathogenesis and severity of COVID-19.