In a comparison of patients stratified by COVID-19 severity, ACE2 was higher in those with severe (maximum WHO Score 5–7) vs. mild (maximum WHO Score 3–4) disease (2.33 (1.77–4.22) pmol/L vs. 4.63 (2.63–41.03) pmol/L; p = 0.063; Table S9). Here, ACE2 is linked to COVID-19.