Progress of Research and Development on a Sewage COVID-19 Virus Surveillance System

Sponsored by the Health and Medical Research Fund (HMRF) under the Food and Health Bureau and fully supported by the Environment Bureau, a multidisciplinary team led by Professor Tong ZHANG of Department of Civil Engineering, the University of Hong Kong (HKU) has been conducting a research project since October 2020 for detecting SARS-CoV-2 in sewage and exploring the feasibility of establishing a sewage surveillance system in local communities, and providing supplementary information to safeguard public health in Hong Kong.

Due to the spread of epidemic and infectious diseases in recent years, the use of sewage surveillance to monitor diseases has become a rapidly developing field. Internationally, there are no standard methods so far for detecting virus in sewage, nor unified guidelines for interpretation of sewage data. The sewage test protocol adopted by the HKU team is a new method that the team has been optimizing and verifying since April this year.

With full support from the Environment Bureau, this one-year research project was officially launched in October 2020. Up till present, the team has collected more than 300 domestic sewage samples from sewage collection systems in different areas for nucleic acid tests of the new coronavirus SARS-CoV-2. The initial results of the research have demonstrated that the sewage surveillance could be used for the following purposes:

1. Providing early warning signals for COVID-19 outbreak: The research team found that the sewage surveillance results correlated very well with the fourth wave of epidemic outbreaks in Hong Kong since mid-November. The detection rate of viruses in sewage can reflect the overall spread of virus in the community, and could be used as supplementary information to complement clinical testing to provide early warning signals of community outbreak.

2. Tracking the development trend of community outbreak: During the epidemic, the changes in the detection rate of viruses in sewage in different areas can be used to assess the development trend of the epidemic in the community.  The research team will continue to collect a large amount of data for analysis and make reference to the actual clinical diagnosis data to develop a systematic evaluation method and follow-up actions.

3. Complementing the monitoring of estates with infection clusters: In response to the development of the fourth wave of the epidemic, the research team flexibly adjusted the monitoring plan, conducted targeted sampling and analysis at buildings with infection clusters, and provided complementary information for clinical tests.

Following the collation of more comprehensive data, the research team will further determine the most suitable sewage sampling time, scope and quantity, and integrate other clinical and epidemiological data in developing a systematic method for early warning, tracking and evaluating the spread of the COVID-19 as well as taking follow-up actions, with a view to serving as a complementary tool to facilitate decision-making in fighting the virus.

As regard to medical and public health aspects, the research team received valuable advice and guidance from Professor Gabriel Leung, Dean of Li Ka Shing Faculty of Medicine, the University of Hong Kong. Professor Leung believes that this research will play a positive role in Hong Kong as well as around the globe in the efforts of fighting the virus together.

Hong Kong has a unique geographical setting with densely populated areas, featuring complex sewerage system, narrow landscape and heavy road traffic. Identifying suitable sampling points and collecting enough number of sewage samples are extremely challenging, yet key to the success of the research. In this regard, the HKU team received continuous facilitation and technical support from the Drainage Services Department and Environmental Protection Department of the HKSAR Government, which is pivotal to the smooth progress of this project.

The team comprises five experts in the field of environmental microbiome and public health. Professor Tong Zhang is the Principal Investigator of HKU’s Environmental Microbiome Engineering and Biotechnology Laboratory. He is a pioneer in applying DNA and RNA technology to study environmental microbiome and has more than 20 years’ experience in the field of environmental microbiology. Other team members include Professor Leo Lit Man Poon, Professor Malik Peiris, Professor Gabriel Leung, and Dr. Hein Min Tun of the School of Public Health, Faculty of Medicine of HKU. Professor Poon and Professor Peiris lead the WHO Reference Laboratory for COVID-19 diagnostics at HKU and are well-known for their extensive expertise in developing testing methods for emerging virus of public health concerns, including SARS-CoV-2. Professor Gabriel Leung is the Dean of Li Ka Shing Faculty of Medicine at the University of Hong Kong, and an expert on infectious disease epidemiology.