Only the gene sets of regulation of hemopoiesis, regulation of inflammatory response, mRNA splicing via spliceosome and epithelial cell proliferation were upregulated at the whole transcriptome level during recovery from COVID-19 (Fig. 3a; Supplementary Fig. 2), which contained many transcription factor genes (e.g., DDIT3, NR4A3, ZEB1, KLF10, JUNB, and JUN), phosphorylation regulatory genes (e.g., AREG, DUSP8, OSM, MAP3K8, and SOCS3), and interferon-stimulated genes (ISG; e.g., TNF, IL1B, CXCR4, CD69, and IER5) (Fig. 3b). Here, DDIT3 is linked to COVID-19.