On Day 3 in the COVID-19 patients (N = 10), systemic arterial ET-1 levels remained unchanged as compared to admission [2.31 (1.78–4.60) pg/mL; p = 0.7], whereas central venous ET-1 levels decreased [2.62 (1.43–5.67) pg/mL; p = 0.4], albeit not statistically significantly. Here, EDN1 is linked to COVID-19.