MX1 and viral infectious disease: First, SARS-CoV-2 infection was associated with upregulation of MX1, a protective factor whose expression was reported to be switched-on in several viral infections including SARS-CoV-2 (Sironi et al., 2014; Haller et al., 2018; Bizzotto et al., 2020; Haller and Kochs, 2020).