Stool Test Could Better Detect COVID-19 than Traditional Nose Swabs Due to Prolonged Gut Viral Infection

Researchers from the Faculty of Medicine of The Chinese University of Hong Kong (Sha Tin District, Hong Kong) found that COVID-19 patients have active and prolonged gut viral infection, even in the absence of gastrointestinal (GI) symptoms. After respiratory clearance of coronavirus, the activity of viral infection and replication still persists in the gut. To better understand the activity and infectivity of COVID-19 virus in the GI tract during the disease’s course, the researchers investigated the stool samples of 15 COVID-19 patients in Hong Kong. The researchers found that there was active gut viral infection in seven patients even in the absence of GI symptoms. Three patients continued to display active viral infection up to six days after clearance of the virus from their respiratory samples. The researchers also found that gut microbiota of patients with high SARS-CoV-2 infectivity were characterized by enrichment of pathogens and loss of “good” bacteria that are capable of producing short-chain fatty acid.

Earlier studies have found that the COVID-19 virus was detectable in the stool samples of all patients, regardless of the degree of illness. The researchers undertook screening of more than 128 stool samples of Hong Kong airport arrivals that revealed six children with confirmed COVID-19 infection and a detection rate of 0.28%. The researchers believe that stool screening test can help identify asymptomatic people carrying the COVID-19 virus as early as possible in order to stop its spread in the community.

“The viral load in the stool of infant and children is many times higher than that in adults, and could be equivalent to that of adult respiratory samples,” said Professor Paul Kay Sheung CHAN, Chairman of the Department of Microbiology and Associate Director of the Centre for Gut Microbiota Research. “The activity of viral infection and replication also persist longer in the guts of infant and children. Stool specimens are more convenient, safe and non-invasive to collect in the paediatric population and can give accurate results. This makes stool test a better option for COVID-19 screening in babies, young children and those whose respiratory samples are difficult to collect.”

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