The close connection between bacterial and viral infection is highlighted by recent work on mechanisms leading to gut dysbiosis in COVID-19, showing that SARS-CoV-2 can induce dysbiosis by triggering intestinal inflammation, by dysregulating the angiotensin-converting enzyme 2 (ACE2), which is essential for amino acid metabolism, and by infection of intestinal bacteria [36,37]. Here, ACE2 is linked to infection.