Patients with COVID‐19 had higher levels of endocan at baseline compared to the control group (3.4 ng/mL [IQR: 1.8–7.5] vs. 1.6 ng/mL [IQR: 1.0–2.1], respectively, p = 0.0031). However, there was no significant difference between patients who progressed ARDS and patients who did not 3.7 [2.8–9.6] ng/mL vs. 3.2 [1.5–5.7] ng/mL, respectively, p = 0.2231). Endocan levels significantly increased in patients with mild/moderate ARDS at the 3–4 (p = 0.0084) and 5–6 days (p = 0.0107), whereas patients with severe ARDS had no increase. The gene discussed is ESM1; the disease is acute respiratory distress syndrome.