ISG15 and infection: Specifically, twelve of them (IFITM1, IFI44L, IFI6, ISG15, XAF1, LY6E, MX1, IRF7, OAS1, EIF2AK2, TRIM22, and TXNIP) showed increased expression during COVID−19 and later declined in the convalescent condition; however, six DEGs (RGCC, LMNA, ZFP36, MT-ND6, JUN, and FOS) showed the opposite; i.e., the expression levels of these genes were reduced during infection with COVID-19 and recovered after being restored to health (Figure 2F and Table S1).