BACKGROUND: To investigate the potential beneficial effect of fecal microbiota transplantation (FMT) on gastrointestinal symptoms, gut dysbiosis and immune status in discharged COVID-19 patients.

CASE PRESENTATION: A total of 11 COVID-19 patients were recruited in April, 2020, about one month on average after they were discharged from the hospital . All subjects received FMT for 4 consecutive days by oral capsule administrations with 10 capsules for each day . In total , 5 out of 11 patients reported to be suffered from gastrointestinal symptoms, which were improved after FMT . After FMT, alterations of B cells were observed, which was characterized as decreased naive B cell (P = 0.012) and increased memory B cells (P = 0.001) and non-switched B cells (P = 0.012) .The microbial community richness indicated by operational taxonomic units number, observed species and Chao1 estimator was marginally increased after FMT . Gut microbiome composition of discharged COVID-19 patients differed from that of the general population at both phylum and genera level, which was characterized with a lower proportion of Firmicutes (41.0 %) and Actinobacteria (4.0 %), higher proportion of Bacteroidetes (42.9 %) and Proteobacteria (9.2 %). FMT can partially restore the gut dysbiosis by increasing the relative abundance of Actinobacteria (15.0 %) and reducing Proteobacteria (2.8 %) at the phylum level . At the genera level, Bifidobacterium and Faecalibacterium had significantly increased after FMT .

CONCLUSIONS: After FMT, altered peripheral lymphocyte subset, restored gut microbiota and alleviated gastrointestinal disorders were observe, suggesting that FMT may serve as a potential therapeutic and rehabilitative intervention for the COVID-19.