Bulletin No. 1, 2020

The Corona Chronicle 25 idea of hidden infections in Hong Kong. The research team aims at recruiting 3,000 subjects, who would provide samples of their blood, saliva, or both. These fluids would be tested for certain antibodies, marks of an infection in the past. The point of searching for hidden patients, said Professor Chan, is to see if our response to the pandemic needs any adjustment. ‘Let’s say our research indicates a considerable number of hidden infections among senior citizens over 65. It could be a sign that our strategy has failed to cover these people all along. In that case, we’ll have to consider, say, enhancing preventive measures and testing at elderly homes.’ The team is also paying attention to the hidden patients’ occupations, trying to understand the risk a particular line of work entails. The study began in late April. In the first phase, the team looked for 1,000 people. There was much enthusiasm for the project, which attracted over 2,000 registrations the first day it was announced. With the data obtained at the pilot stage, the team could generate an estimate for the number of hidden infections in the city and decide on what to do next, which could involve contact tracing and focusing its research on particular age groups. A s we stayed home to wait out the pandemic, medical professionals stayed in their wards, racing against the clock to save lives and defeat the disease. Joining the ranks were physicians from the Faculty of Medicine, part of whose work during the pandemic was designing a stool test for children arriving in Hong Kong by air. This project was based on an investigation by the Faculty which showed that the virus was detectable in the stool samples of all patients, regardless of how sick they were. Indeed, 20% to 30% of the patients cleared of the virus in their respiratory tracts tested positive in their stool samples. In light of these findings, the Faculty arranged for stool test kits to be distributed to children arriving at the Hong Kong International Airport starting 29 March. A laboratory here at CUHK would then test the specimens and have the results ready within a day. Children can remain asymptomatic when infected, and it is crucial that silent carriers are detected if we are to prevent an outbreak in our community. The stool test came as an improvement on the deep-throat saliva test. It is difficult to collect saliva from a child’s throat, as Prof. Paul Chan , Chairman of the Department of Microbiology, noted. With improper collection techniques, the test yields a false negative rate of 40%. Stool samples, on the other hand, are easier to collect when it comes to children and give more accurate results. By the end of May, over 700 stool tests had been performed. Apart from detecting active asymptomatic cases, Professor Chan also started identifying those who have previously been infected to get a full Prof. Paul Chan Chairman of the Department of Microbiology Clinical Services to the Community