In the COVID-19 group, coagulation factor XIII A chain (F13A1) and contactin associated protein 2 (CNTNAP2) exhibited the strongest upregulation, with CD14, C1QC, cytochrome C oxidase subunit 7C (COX7C) and (APOE) being increased in the AD group (Figure 4B). Here, APOE is linked to COVID-19.