The loss of butyrate-producing anti-inflammatory bacteria (e.g., Faecalibacterium and Roseburia) as well as the upregulation of proinflammatory mediators (e.g., CRP, IL-6 and soluble IL-2 receptor (sIL2R)) was more pronounced in severe/critical COVID-19 patients than mild patients (92). Here, CRP is linked to COVID-19.