Probiotics and antimicrobial proteinsAug 29, 2026

Gut Bacteria from People with Long COVID for 2 Years Cause COVID-Like Symptoms in Mice

Updated Aug 30, 2026

Abstract

Fecal microbial diversity was lower in patients with long COVID compared to healthy controls (n=11 each).

Patients with long COVID exhibited an increase in pro-inflammatory bacteria like Streptococcus salivarius and Streptococcus parasanguinis.
There was a decrease in anti-inflammatory bacteria such as Faecalibacterium SGB15346 and Alistipes onderdonkii among long COVID patients.
Fecal metabolites from long COVID patients showed impairments in carbohydrate degradation, indole production, short-chain fatty acid production, and fatty acid degradation.
Transplanting feces from long COVID patients into mice led to lung and intestinal inflammation, as well as increased anxiety.
Mice that received fecal transplants demonstrated worse outcomes during infections with Klebsiella pneumoniae.
The significant alterations in the gut microbiota of long COVID patients may promote long COVID symptoms in mice.

Simplified

Human gut microbiota (GM) has been identified as a potentially important factor influencing the development of long COVID (LCOVID). The aim of this study was to understand the GM of LCOVID, which lasted for two years, in order to improve public awareness. Human gut microbiota and its metabolites were assessed in a healthy control group (n = 11) (HC) unexposed to SARS-CoV-2 and an LCOVID group (n = 11) in Hainan, China, using Shotgun metagenomics and liquid chromatography-mass spectrometry (LC-MS) of feces. The causal role of the microbiota in LCOVID was further validated by transplanting feces from the subjects into ABx mice using Histopathology and 16 S rRNA sequencing. Fecal microbial diversity was lower in patients with LCOVID compared with that in HC. Pro-inflammatory bacteria such as Streptococcus_salivarius and Streptococcus_parasanguinis increased, whereas anti-inflammatory bacteria such as Faecalibacterium_SGB15346 and Alistipes_onderdonkii decreased. Fecal metabolites from LCOVID were impaired in carbohydrate degradation, indole production, SCFA production, and fatty acid degradation. Transplantation of feces from patients with LCOVID into mice results in lung inflammation, intestinal inflammation, and anxiety. In addition, transplanted mice showed worse outcomes during Klebsiella_pneumoniae infections. Transplanted mice and the key bacteria Streptococcus_salivarius had the same worse outcomes in the D-IBS model by limb binding. GM from patients with LCOVID was altered significantly and sufficiently to promote LCOVID symptoms in mice, suggesting that it may be a potential therapeutic target.

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Gut Bacteria from People with Long COVID for 2 Years Cause COVID-Like Symptoms in Mice

Abstract

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