Furthermore, we observed significantly higher expressions of complement genes C4A, C4B, and complement component 1 Q subcomponent receptor 1 (C1QR1), and inflammatory genes such as IL-4R, CXCL1, nuclear factor of activated T cells 5 (NFAT5), and colony-stimulating factor 1 (CSF1) in ORF8(+) amnion tissues when compared with ORF8(-) COVID-19 amnion tissues (Fig. 4G,H). Here, C4A is linked to COVID-19.