A man walks across a basketball court in the Choi Hung public housing estate, Hong Kong, on July 5, 2020. (ISAAC LAWRENCE / AFP)

HONG KONG - Residents at another Hong Kong public housing estate will be subject to mandatory testing as four samples from the block’s sewage tested positive for COVID-19.

No COVID-19 patient had been reported, however, at Fung Chak House in Choi Wan (II) Estate, said Gabriel Leung, dean of the University of Hong Kong (HKU)’s Faculty of Medicine at a briefing on Monday.

The government issued a notice at Monday noon that residents at the block should get tested before Dec 31. Mobile specimen collection stations will be set up adjacent to the building at Choi Hung in Wong Tai Sin district of Kowloon. 

Gabriel Leung, dean of the University of Hong Kong’s Faculty of Medicine, stressed that the findings did not mean the virus would be transmitted to other residents through the estate’s sewage system

The block is close to Ming Lai House in Choi Wan (II) Estate where 15 people have been confirmed as infected and on Dec 16, the last patient there was quarantined.

ALSO READ: CE warns fourth wave could well take a serious turn

Leung said the positive samples, which were taken from the block from Wednesday through Sunday, indicate that there could be asymptomatic patients or silent transmissions in the block, and that mandatory testing could avoid a cluster outbreak.

“The virus was likely spread by those who used the block’s washrooms,” said Leung, who stressed that the findings did not mean the virus would be transmitted to other residents through the estate’s sewage system.

A sewage surveillance system for detecting SARS-CoV-2, conducted by HKU researchers and sponsored by the government, was established in October and will last for a year. More than 300 sewage samples across the city have been tested so far.

“The results provide some early warnings before the first confirmed case (comes to the fore),” said Zhang Tong, professor at the Department of Civil Engineering of HKU, who led the research. “...We need to consider other clinical results and also epidemiological data together. The sewage surveillance is supplementary to the whole decision-making framework of (public health).”

Hong Kong saw 70 new COVID-19 cases on Sunday, including 69 that were locally transmitted and 23 of them remained untraced.

READ MORE: CE vows to expand community testing to curb COVID-19