The fecal virus load of SARS-CoV-2 in severe COVID-19 patients were found to be inversely correlated with 4 Bacteroides species, i.e., Bacteroides dorei, Bacteroides thetaiotaomicron, Bacteroides massiliensis and Bacteroides ovatus, which could downregulate the expression of ACE2 in the murine colon (Geva-Zatorsky et al., 2017; Zuo et al., 2020c). This evidence concerns the gene ACE2 and COVID-19.