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Gut bacteria may play a role in the development of long COVID

• Many people who recover from COVID-19 report lingering symptoms such as fatigue, muscle weakness, and insomnia, known collectively as post-acute COVID syndrome (PACS) or long COVID.
• Previous research has found that individuals who experience severe COVID-19 tend to have gut dysbiosis, a disruption in the community of microorganisms living in the gut.
• A new study has found the first evidence that there may also be a connection between gut dysbiosis and long COVID.
• Future clinical trials could therefore investigate probiotics, dietary changes, or fecal transplants as potential treatments for long COVID.

As many as three-quartersTrusted Source of people who recover from COVID-19 report experiencing at least one lingering symptom 6 months later.

Common symptoms of this condition, known as PACS or long COVID, include fatigue, muscle weakness, and insomnia.

The exact cause of long COVID remains a mystery, but possible contributory factors are excessive immune responses and cell damage sustained during the illness itself.

It also remains unclear why some people who have had COVID-19 experience lingering symptoms for weeks or months while others recover completely.

In 2020, researchers at the Center for Gut Microbiota Research, part of the Chinese University of Hong Kong, found a clue.

They discovered that people with COVID-19 had distinct changes in their gut microbiota, the community of microorganisms living in their gut, compared with healthy controls.

The collection of genomes of the gut microbiota is known as the gut microbiome.

Fecal samples from people with COVID-19 contained more opportunistic pathogens or disease-causing organisms and fewer “friendly” bacteria.

This disruption in the balance of organisms living in the gut, known as gut dysbiosis, appeared to be more extreme in people with more severe illness.

Because the gut plays a major role in the regulation of the immune system, disturbances in the gut microbiota may not only exacerbate COVID-19 but also cause lingering symptoms as a result of continuing immune disturbances.

The Center for Gut Microbiota Research has now found the first evidence of gut dysbiosis in people with long COVID up to 6 months after their initial SARS-CoV-2 infection.

The scientists found links between specific groups of bacteria and particular symptoms.

At the time of hospital admission, people who went on to develop long COVID tended to have a less diverse and abundant microbiome compared with people who fully recovered.

In fact, the gut microbiome of people who did not develop long COVID was similar to that of a group of healthy controls who provided fecal samples before the pandemic.

The results of the study appear in the journal Gut.

Potential treatments

“Our study demonstrated the association between [a persistently] altered gut microbiome and long COVID, which also suggests that there is an opportunity to ameliorate these symptoms by regulating the gut microbiome,” said Prof. Siew C. Ng, Ph.D., associate director of the Center for Gut Microbiota Research and senior author of the new study.

“There are important implications for future research regarding the mechanisms of disease underlying long COVID where most have tended to ignore the gastrointestinal system, and also for trials of potential therapies and diagnostic approaches,” she told Medical News Today.

She added that possible treatment approaches might include diets that support a healthy and balanced gut microbiota, avoiding antibiotics where possible, probiotic supplements to replace depleted bacterial species, and fecal microbiota transplants.