Stool-based Testing Developed by CU Medicine Crucial for Early Detection of Asymptomatic COVID-19

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An improved testing method for COVID-19 by analyzing stool samples was developed by the Faculty of Medicine at the Chinese University of Hong Kong (CU Medicine) to help curb the spread of the virus. Proven to be useful in identifying early infections of COVID-19, especially among asymptomatic children, the stool test has been implemented in Hong Kong to minimize spread in the community.

Once the outbreak of COVID-19 was recognized in Hong Kong, CU Medicine pioneered to analyze a variety of specimen types collected from confirmed cases. Remarkably, all patients had their stool tested positive during their course of illness, regardless of its degree; and more than 20% of the patients still had the virus in their stool samples, even after it was no longer found in their respiratory samples. This finding carries important implications on the control of transmission in the community and testing strategy to improve case identification.

The finding has led to the development of a non-invasive and accurate COVID-19 stool test by CU Medicine to overcome the difficulty in collecting respiratory samples by parents at home.

Working with the Hong Kong SAR Government, stool test kits have been distributed for free to children arriving at the Hong Kong International Airport since late March. CU Medicine has been processing the stool specimens in its laboratory and providing the results to the Hong Kong Government to follow up on the positive cases the next day after the specimens are received.

Virus shedding in the stool may have public health implications, according to Professor Francis KL CHAN, Dean of the Faculty of Medicine and Director of the Centre for Gut Microbiota Research at CUHK. Apart from serving as an alternative screening tool in people without respiratory symptoms, virus shedding in the stool may impose health hazard to others. In this light, caretakers and food handlers should be particularly vigilant about their hand hygiene in order to mitigate the virus from spreading.

In addition to developing the stool test, the CU Medicine team led by Professor Paul KS CHAN, Chairman of Microbiology Department, is taking the lead to investigate hidden infections in Hong Kong to help improve containment strategies and support the community to better prepare for the future waves of COVID-19.

Please visit CUHK’s one-stop information portal “Act together against COVID-19” for related initiatives, experts’ analysis and advice, and e-learning resources.