Government staff members check whether a resident in the "restricted area" at 35-37 Nam Cheong Street, Sham Shui Po has undergone compulsory testing, Hong Kong, Jan 21, 2022. (PHOTO/HKSAR GOVERNMENT)

HONG KONG – Around 50 people were tested in a targeted testing operation in Sham Shui Po overnight and no positive COVID-19 cases were detected.

The government set up a “restricted area” at 35-37 Nam Cheong Street at 7 pm Friday after a construction worker who lives there tested preliminarily positive for the coronavirus. His source of infection remained unknown.

At the same time, the government cordoned off Ying Kwai House at Kwai Chung Estate, Kowloon for another targeted testing Saturday morning after three infections were found there

The 40-year-old man, who has been fully vaccinated, last went to work on Jan 19, the Centre for Health Protection said in a statement.

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The CHP is investigating the places where he visited during the incubation period to ascertain the infection sources.

The testing exercise was completed around 7 am Saturday. Five households did not answer the door and the government said they will carry out follow-up actions.

At the same time, the government cordoned off a building in Kwai Chung Estate for another targeted testing after three infections were found there.

The "restricted area" was set up at Ying Kwai House at 4 am Saturday after authorities found one confirmed case and two suspected ones there.

Residents are required to undergo compulsory testing before 1 pm Saturday. The government expected to finish the exercise at around 7 pm the same day.

The government announced a five-day lockdown of Yat Kwai House – another block on the estate –  Friday evening after a major outbreak there.

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The action came after the block saw more than 20 COVID-19 cases involving 12 floors and 13 units,  with most of them suspected Omicron infections.

The government reminded members of the public that anyone who fails to comply with the compulsory testing notices commits an offense and may be fined a fixed penalty of HK$5,000.