To identify practical prognostic indicators in severe COVID-19 patients, we focused on two proteins, namely chitinase-3-like protein 1 (CHI3L1) and insulin-like growth factor-binding protein acid labile subunit (IGFALS), since statistical analyses showed that high and low levels of these proteins, respectively, were significantly correlated with adverse prognosis in severe COVID-19 patients (Table 1). The gene discussed is CHI3L1; the disease is COVID-19.