CCL4 and COVID-19: All the five protective proteins, namely, C-X-C motif chemokine 11 (CXCL11), CUB domain-containing protein 1 (CDCP1), macrophage inflammatory protein CCL4/MIP, Interferon Gamma (IFNG) and leukemia inhibitory factor receptor (LIFR), were associated with a decrease in the risks of being hospitalized with COVID-19 and of developing critical COVID-19 (OR: 0.85~0.95) (Table 1 and Figure 1).