October 21, 2020

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HKU team to study sewage for COVID-19 virus detection

A cross-disciplinary team led by Professor Tong Zhang of the Department of Civil Engineering and supported by the “COVID-19 Action Seed Funding” of the Faculty of Engineering at the University of Hong Kong, has received funding from the government’s Health and Medical Research Fund to develop a methodology for the detection and monitoring of SARS-CoV-2 in sewage to supplement the overall community surveillance system. The study will start in mid-October 2020.

In the past few months, the presence of SARS-CoV-2 nucleic acid in sewage was reported in various countries and regions. These occurrences may even be dated back to before any awareness of virus circulation in those communities. The recent development in sewage testing for SARS-CoV-2 may lead to new measures for public health surveillance, for early detection of COVID-19 emergence.

However, there is currently no standardised method for surveying COVID-19 in municipal sewage. The key experimental steps in the pre-treatment of sewage samples, as well as the detection and quantification processes in the context of Hong Kong, have yet to be systematically evaluated and optimised.

Since 1 April 2020, the cross-disciplinary team has been working to optimise the protocol, validating the methodology and conducting preliminary tests with spiked samples. They have developed methods suitable for detecting SARS-CoV-2 in sewage in Hong Kong by using a centrifugal filter for pre-concentration.

With the strong support from the Drainage Services Department and Environmental Protection Department, the research team has been conducting a couple of projects (including one funded by Health and Medical Research Fund to be kicked off in October) on the surveillance of SARS-CoV-2 in the sewerage network.

The data from sewage can be used to inform the presence and spread of the virus in district-specific communities, even when individuals’ data are not yet available. The results could complement current clinical and laboratory surveillance effort.

The Professor stated that now is a good time to establish the general principles and explore suitable practices for the feasibility of a long-term sewage monitoring methodology to proactively identify and respond to future outbreaks of COVID-19 in Hong Kong.

According to another article, after spending months combating three waves of Covid-19 infections, Hong Kong is now trying to gain an upper hand against the virus. With a potential fourth wave looming, the city’s government is currently exploring previously unused pandemic surveillance methods – including rapid tests, technologically-assisted contact tracing and even monitoring the virus in sewage –to better detect community outbreaks before they spiral out of control.

However, even as the city is preparing for a lift in pandemic-related restrictions, health experts caution against the belief that new technologies are a silver bullet – public vigilance in practising social distancing will remain key to fighting the coronavirus.

For some time now, the city has been tracing local transmissions by tracking close contacts of patients and testing high-risk groups, but now the government is considering gathering environmental evidence as well.

The HKU system for monitoring the level of Sars-CoV-2 in sewage is being set up in collaboration with the government, including the Drainage Services Department and Environmental Protection Department.

The Dean of HKU’s medical school and a government adviser on pandemic strategies stated that experts have been identifying the particular drains and manholes, and streets and sewage collection points that are needed for the surveillance system to work. The system will help spot an imminent outbreak or limit the spread of an existing one by quickly testing residents in the nearby blocks and areas, and isolating them.

The Head of HKU’s school of public health stated, “In reality, some technologies may lessen the need for some measures, but we are still going to need a combination of public support and participation in measures such as social distancing, and good decisions from the government about when and how to relax or stand up such prevention and control measures.”