With the generous support of Fok Ying Tung Foundation, LKS Faculty of Medicine, The University of Hong Kong (HKUMed) is launching a real-time community surveillance initiative to assess and monitor the underlying epidemic dynamics of COVID-19 infection during the ongoing fifth wave of Omicron BA.2.
A total of 10,000 participants will be recruited from HKUMed's several large-scale longrunning cohorts and ongoing studies (e.g. FAMILY cohort, Children of 1997 Birth Cohort, Elderly Health Services Cohort, Flu in family cohort, serological surveys) currently maintained by the School of Public Health, also supplemented by randomly drawn samples from all 18 districts around Hong Kong.
The current fifth wave has led to unprecedented disruption to societal functioning and imposed a massive care burden to the health system. Polymerase chain reaction (PCR) testing, whether by self-provided deep throat saliva samples or professionally administered swabbed samples, suffer from three major shortcomings rendering the reliability of reported case counts as being an accurate reflection of the real epidemic trajectory in some doubt.
First, there is ongoing supply constraint of total testing capacity. Second, those presenting for PCR testing is increasingly a biased population due to recent frequent changes to the issuance of restriction testing declarations (RTDs), compulsory testing notices (CTNs), as well as population behavioural adaptation to the consequences of the possibility of a positive result. Third, population behavioural change has been compounded by the increasingly easy availability of rapid antigen tests (RATs). Finally, with widespread circulation of the virus, the previously indicative sewage surveillance signal is no longer useful in tracking epidemic trajectory.
It is however more critical than ever to maintain reliable surveillance of (at least relative) epidemic growth or decline, in order to provide real time input into policy decisions.
The community surveillance initiative will commence as soon as possible for a continuous period of 12 weeks in the first instance. RATs and lateral flow immunoassays (LFIAs) for SAR-CoV-2 antibodies will be provided to all participants, who will carry out RATs on a weekly basis with self-sampled combined throat and nasal swab, and LFIAs with a drop of capillary blood sampled by self-finger prick on a monthly basis. Parents may collect samples for their children. All testing results will be reported through an online reporting platform of the real-time surveillance system. The data collected will be robustly prosecuted, enabling researchers to estimate how quickly the virus is spreading in the community, and to estimate the proportion of the people having antibodies to SARS-CoV-2 in real-time among the local population, due either to vaccination or prior infection with the virus. These data streams will enable researchers to provide an unbiased assessment of the underlying epidemic dynamics, on which basis epidemic control decisions are to be made.
'We are most grateful to the Fok Ying Tung Foundation for making the community surveillance initiative possible, which will provide real-time data for continuous monitoring of epidemic dynamics of the ongoing fifth wave. This will be invaluable for decision making,' said Professor Gabriel Leung, Dean of Medicine, The University of Hong Kong, Helen and Francis Zimmern Professor in Population Health, and Chair Professor of Public Health Medicine, HKUMed.
