In the context of COVID-19, since ACE2 is highly expressed in the gastrointestinal (GI) tract (9), shedding the virus in the stool is prolonged (10); however, diarrhea is uncommon likely because virus-specific effector memory T cells typically home to the mucosal surfaces they had previously encountered with an infection with a common CoV, i.e., upper and lower respiratory tract. Here, ACE2 is linked to COVID-19.