1. General Influence of Gut Microbiota on SARS-CoV-2 Infection.

factor	effect on SARS-CoV-2 infection	refs
decrease in Bifidobacterium and Lactobacillus	weakens intestinal barrier, increases inflammation	−
gut dysbiosis	increases intestinal permeability, worsens COVID-19 severity	−
short-chain fatty acid (SCFA) production	modulates immune response, potential protection against severe infection	−
antibiotic use	reduces microbial diversity, negatively impacts recovery	−
probiotics and prebiotics	potential beneficial effects on immune regulation and inflammation reduction	−