Furthermore, hyperactivation of the vagus nerve downregulated the expression or activity of ACE2 which could even potentially prevent viral infection via the ACE2 entry point (Fudim et al., 2020) (see also Osterziel et al., 1994; Duprez et al., 1995; Cody, 1997; Karas et al., 2005; Zucker et al., 2014; Liu et al., 2015). This evidence concerns the gene ACE2 and viral infectious disease.