CUHK study identifies gut microbial profile associated with long COVID

9 March 2022

For some people, COVID-19 can cause symptoms that last weeks or months after the infection has gone. This is sometimes called post-COVID-19 syndrome or “long COVID”.

A study conducted by the Chinese University of Hong Kong’s Faculty of Medicine showed that gut bacteria may be linked to a person’s risk of developing long COVID.

In this study long COVID was defined as the presence of at least one persistent symptom for four weeks after clearance of the SARS-CoV-2 virus. Some 76% of patients had at least one symptom six months after recovery from COVID-19 infection.

The study found that patients with long COVID had a less diverse gut microbiome, while the gut microbiome of patients who did not develop long COVID was similar to that of those who did not have COVID-19. Patients with long COVID had significantly fewer favourable bacteria and a greater abundance of unfavourable bacteria than people who did not have COVID-19.

Researchers looked at the composition of the gut microbiome to see if it was associated with different categories of long COVID symptoms, including respiratory, neuropsychiatric, gastrointestinal, hair loss, musculoskeletal and fatigue. Eighty-one bacterial species were associated with different categories of long COVID and many species were associated with more than two categories of persistent symptoms.

The research was conducted by a team led by Professor Ng Siew Chien and published in Gut. “Considering the millions of people infected during the ongoing pandemic, the findings are impetus for consideration of microbiota modulation to facilitate timely recovery and reduce the burden of post-acute COVID-19 syndrome,” said Professor Francis KL Chan, Dean of Medicine at the Chinese University of Hong Kong who was also involved in the research.