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A randomised, double-blind, placebo-controlled trial (RECOVERY STUDY) conducted by The Chinese University of Hong Kong (CUHK)’s Faculty of Medicine (CU Medicine) and Microbiota I-Center (MagIC) showed that an oral microbiome microencapsulated formula (SIM01) led to significant improvements in gut microbiota composition and alleviation of long COVID symptoms.

The study has profound implications for the role of gut microbiota modulation in improving symptoms in people with long COVID. The landmark findings have recently been published in The Lancet Infectious Diseases, a publication from The Lancet Group.

World’s first large-scale study discovers an effective treatment for long COVID

Long COVID refers to long-term symptoms involving multiple systems and organs that persist in recovered COVID-19 patients. Currently, it affects 40% of these patients worldwide, yet the mechanism remains unknown and effective treatment is lacking.

The research team has previously shown that patients with long COVID lacked a series of beneficial gut bacteria, which may contribute to multiple symptoms. Using big data and machine-learning analysis, CUHK developed a patented oral microbiome microencapsulated formula (SIM01). From 2021 to 2022, 463 patients were randomly assigned to receive SIM01 or placebo. At six months, significantly higher proportions of the SIM01 group had experienced alleviation of five key symptoms – gastrointestinal upset, fatigue, difficulty in concentration, memory loss, and general unwellness – compared with the placebo group (the alleviation rates were 70%, 63%, 62%, 42% and 77% respectively). Adverse event rates were similar between groups during treatment. SIM01 also significantly enhanced the diversity and richness of the gut microbiota, promoted the growth of multiple beneficial bacteria, and inhibited potentially pathogenic bacteria, thereby maintaining microbial balance.

Maintaining balanced gut microbiota is key in preventing infectious diseases and long-term symptoms

Professor Siew Ng, CU Medicine’s Croucher Professor of Medical Sciences and Director of MagIC, stated, “This is the first clinical trial to show that modulation of the gut microbiota can improve long COVID symptoms. The study also highlighted important mechanisms underlying the benefits of SIM01. The intervention not only led to increased gut microbiota diversity, richness and microbial function, but also enhanced the production of metabolites from beneficial gut bacteria, including short-chain fatty acids, which can circulate to the brain. These findings supported the importance of the gut-brain axis, and that modulation of the gut microbiota represents a novel approach to improving neurological symptoms.”

Professor Francis KL Chan, Dean of Medicine and Director of the Centre for Gut Microbiota Research at CU Medicine, concluded, “Maintaining balanced gut microbiota is key in preventing emerging infectious diseases and persistent symptoms after recovery from the acute infection. As we are at risk of grappling with a surge in respiratory infections during the winter, the public should consider timely microbiota modulation to reduce the risk of infections and their related long-term symptoms.”

The RECOVERY STUDY was supported by the InnoHK initiative, and the Health and Medical Research Fund from the Government of the Hong Kong Special Administrative Region.