Probiotic Mitigates Long COVID by Reshaping Microbiome and Reducing Histamine Burden

Gut dysbiosis is a pathogenic hallmark of Long COVID, yet targeted therapeutic mechanisms remain undefined. Herein, we performed a longitudinal multi-omics analysis on 695 stool and 476 blood samples collected over 12 months from 280 Long COVID patients enrolled in a randomized clinical trial. Participants received either the synbiotic formula SIM01 (specific Bifidobacterium strains with prebiotics) or placebo for 6 months, alongside clinical symptom tracking. SIM01 induced durable remodeling of gut microbiota composition and function, increasing diversity, enriching beneficial commensals (e.g., A. muciniphila, F. prausnitzii), and depleting potential pathobionts (e.g., R. gnavus).