How a severe Covid-19 infection affects gut health

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Although Covid-19 was primarily a respiratory disease, it significantly affected people’s other organs, including the gut. Researchers from King’s College London observed that the system that would normally regulate the composition of microbial communities – otherwise known as Peyer’s Patches – was severely disrupted by severe Covid-19.

This is regardless of whether or not there is evidence of virus in the gut. While severe Covid-19 can lead to breathing problems and high fever, some patients may experience diarrhea, nausea and vomiting, suggesting involvement of the gastrointestinal tract.

“This study shows that in severe Covid-19, this key component of the immune system is disrupted whether or not the gut itself is infected with SARS-CoV-2,” said Professor Jo Spencer, from King’s College London.

“This would likely contribute to the disruptions of gut microbial populations in Covid-19 reported by others,” Spencer added.

The study, published in the journal Frontiers in Immunology, looked at samples of the gastrointestinal tract from patients who died after being diagnosed with Covid-19 during the first wave of the pandemic.

Observations of the samples revealed that the structure and cellularity of Peyer’s patches – a group of lymphoid follicles that line the small intestine – had been altered independently of local levels of the virus.

This included the depletion of germinal centers, which normally spread antibody-producing cells, in patients who died with Covid.

The resulting low local immunity could lead to reduced microbial diversity, known as dysbiosis.

Lymphoid tissue in the gut normally maintains healthy gut microbial populations that are essential for good health.

The researchers also noted that the results suggest that oral vaccination may not be effective if the patient is already sick, because the gut immune system is already compromised.

“In the future, it will be important to understand the factors driving such lymphoid tissue dysregulation in severe inflammatory responses,” Spencer said.

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