CCL2 and acute respiratory distress syndrome: Despite the fact that expression of revealed ALI/COVID-19-related core genes has been analysed in post-mortem lung tissues of COVID-19 patients [82], it was recently shown that a range of these genes (CCL2, MMP8, IFI44, LCN2, SAA1) were also differentially expressed in plasma, BALF and nasopharyngeal/saliva samples of COVID-19 patients and were significantly correlated with the severity of COVID-19 and unfavorable clinical outcomes [118, 124–127].