Furthermore, many senescence-associated genes, such as KIR2DL3, KIR3DL2, USP18, B3GAT1, and KLRC1/D1/K1, and the genes that were involved in Notch signaling, such as Notch receptor (Notch1/2), regulator (DTX2/3/4), target (HEY2, HES7) and cell cycle (CCND1, CDKN1B, CDK3/6) were all markedly downregulated in children with COVID-19 (Supplementary Figure 10). This evidence concerns the gene CCND1 and COVID-19.