Specifically, the depletion or enrichment of above listed key bacterial and fungal species in COVID-19 patient samples were associated with downregulation of the anti-inflammatory IL-4 signaling and associated with upregulation of IL-2, IL-3, IL-5, IL-6, IL-7, IL-10, IL-20, IL-22 and IL-23 signaling, IFNα signaling pathways, TGFβ signaling pathways, inflammatory pathways, and immune dysregulation. Here, IL4 is linked to COVID-19.