CD4 and COVID-19: By integration analysis, a total of 9 ICD-related genes (TLR4, HSP90AA1, PIK3CA, BAX, ENTPD1, CD4, CASP1, FOXP3, TNF) were obtained, which were differentially expressed in both of them, suggesting that these ICD-related genes may be closely associated with the occurrence of severe COVID-19 and immune infiltration.