The make-up of a person's gut microbiome may play a part in the severity of a Covid-19 infection, a new study suggests.
esearchers set out to examine whether the variety and volume of bacteria in the gut, known as the microbiome, played a role in Covid-19 despite it being a respiratory illness.
The team from The Chinese University of Hong Kong examined blood, stool and records from 100 hospital patients with Covid-19.
And 27 participants provided samples 30 days after the infection had passed.
They also collected samples from 78 people without Covid-19 who were taking part in a microbiome study before the pandemic.
The team found that gut microbiome composition was "significantly altered" in patients with Covid-19 compared to people who do not have the disease.
The study concludes that the gut microbiome could be involved in the "magnitude of Covid-19 severity possibly via modulating host immune responses".
The authors found that patients with Covid-19 were depleted in gut bacteria known to modify a person's immune response.
And the composition of the bacteria appeared to persist 30 days after the virus had gone.
Meanwhile, analysis of blood showed that the gut imbalance found in the Covid-19 patients was also associated with raised blood levels of some of the molecules that mediate inflammation.
This suggests that the gut microbiome might influence the immune system response to Covid-19 infection and potentially affect disease severity and outcome, the researchers said.
They said that imbalances in the make-up of the gut microbiome may also be implicated in persisting inflammatory symptoms, like those seen among patients with long Covid.
They concluded: "Bolstering of beneficial gut species depleted in Covid-19 could serve as a novel avenue to mitigate severe disease, underscoring the importance of managing patients' gut microbiota during and after Covid-19."
Daniel Davis, professor of immunology at the University of Manchester, said: "Our knowledge of gut microbes has exploded in recent years. Variations have been associated with diseases as diverse as asthma, multiple sclerosis and cancer.
"So it's perhaps not so surprising that the severity of Covid-19 also correlates with the composition of a person's microbiome."