Microbiome transplants may hold promise for “long COVID-19” as study sheds light on gut connection

12 Jan 2021 --- Microbiome transplants have been proposed as a potential treatment for individuals suffering long-term symptoms of COVID-19. 

This is in light of the discovery that the gut microbiome may influence the severity and longevity of COVID-19 symptoms.

The authors of the observational study say their results show that a healthy microbiome improves the body’s overall immune response to the virus. 

Graham Rook, a microbiology professor who was uninvolved in the study, says the findings could potentially lead to microbiome transplants as a treatment method. 

“It would be exciting if transfer of microbiota from appropriate donors could be used to treat ‘long COVID,’ but more definitive studies will be needed.”

The results indicate a poor microbiome may lead to more severe symptoms in COVID-19 patients.Booming focus on microbiome
Interest in gut microbiome – a term denoting the variety and volume of bacteria in the gut – has grown rapidly over the past decade and has been catalyzed by the COVID-19 pandemic. 

This has boosted public interest in immune strength enormously. 

In order to investigate the connection between the gut and the virus, a cohort study of 100 patients with the COVID-19 in two UK hospitals was launched last year, spanning February to May. 

Stool samples and hospital records were obtained for these patients as well as for 78 additional people who did not have the virus, and who were already participating in an unrelated gut microbiome study before the investigation, now published in the British Medical Journal. 

Can the gut microbiome fight the virus? 
In total, 274 stool samples were collected and analyzed. The samples came both from the patients while suffering from the infection and following their clearance from the hospital. 

Gut microbiome compositions were characterized by shotgun sequencing of total DNA extracted from stools. Concentrations of inflammatory cytokines and blood markers were also measured from plasma. 

The results showed that gut microbiome composition was significantly altered in patients with COVID-19 than non-COVID-19 individuals regardless of whether patients had received medication.

Microbial imbalance found in the COVID patients was also associated with raised inflammatory cytokines and blood markers of tissue damage. 

The researchers say the findings suggest that the gut microbiome influences the body’s immune response to the virus and that the volume of bacteria may therefore be responsible for “long COVID” – the phenomena of symptoms enduring for weeks and months after infection. 

The experts react
Interest in maintaining gut health to prevent COVID-19 symptoms has already grown rapidly.A number of scientific researchers have reacted to the study findings, emphasizing the importance of the results while stressing the need for proportionality, given the limitations of the research. 

“It’s perhaps not so surprising that the severity of COVID-19 also correlates with the composition of a person’s microbiome,” says Daniel M. Davis, a professor of immunology at the University of Manchester. 

“A particularly striking finding was that distinct characteristics in a person’s gut microbes persisted after clearance of the virus. It is possible that these changes could contribute to the symptoms of so-called ‘long-COVID.’” 

“Overall, this new research doesn’t yet lead to a clear public health message in terms of treatments or therapies, but does set the scene for a hugely important realm of new science,” he concludes. 

Kaitlin Wade, a lecturer in epidemiology, also stresses the research’s pitfalls should prevent industry or the public from drawing unwarranted conclusions. 

“The key message here should be one of considerable caution. Although some evidence potentially linking COVID-19 and the gut microbiome has been found, much further and deeper research is required to understand this complex relationship and draw meaningful conclusions.”

Further research underway
The results followed an announcement last year that Danone North America, along with its subsidiary company Activia, is funding an extensive exploration into oral and gut microbiota and its connections with the COVID-19 virus. 

Conducted at Rutgers University, the study is part of a series of clinical trials of US healthcare workers exposed to COVID-19 – one of the nation’s largest prospective studies on the topic.

The investigation aims to determine if virus-exposed healthcare workers’ pre-COVID-19 microbiome is a predictor of COVID-19 infection severity. It will also assess how the novel coronavirus impacts the health of the microbiome.

Edited by Louis Gore-Langton

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