ACE2 and COVID-19: SARS-CoV-2 enters cells via the ACE2 receptor.177 ACE2 is a zinc carboxypeptidase (which cleaves C-terminal Phe from angiotensin II, DRVYIHPF).176 Dexamethasone, a corticosteroid used for treating critically ill COVID-19 patients, induces the Cys-rich protein metallothionein which binds clusters of ZnII and CuI ions.311 Potassium BiIII citrate is in phase III clinical trials (ChiCTR2000030398) for treating the disease.