The CHP’s Dr Albert Au said the patient is a 42-year-old man who lives in Tuen Mun and works in North Point as a surveyor.
Au said the patient tested preliminary positive for a mutant strain of the virus, and has since been sent to the North Lantau Hospital Hong Kong Infection Control Centre for treatment.
He said there is a “high possibility” that the man was infected with the Omicron variant.
It’s the first unlinked case in Hong Kong in more than two months.
Au said the man, who was not vaccinated, had not been in contact with any known Covid-19 patients, or visited any high-risk areas, and he hadn’t been to the Moon Palace restaurant in Festival Walk which is at the centre of a recent outbreak.
He added that authorities are still trying to track the source of the man’s infection.
“As this is an unknown source case, we’re still carrying out epidemiological investigations and contact-tracing so at this stage, we could not find out the source of this case,” Au said.
“This is worrying because this signifies there could already be a silent transmission chain in the community.”
Health authorities on Tuesday evening placed the building in Tuen Mun where the surveyor lives – Block 2 of Tsui Ning Garden on Fung On Street – under overnight lockdown, requiring residents there to be tested.
Officials hope to complete the exercise at about 6:30am on Wednesday.
Meanwhile, a 13-year-old girl who dined at the Moon Palace on December 27 has tested preliminary positive in quarantine.
Her mother was among six diners confirmed to have the virus.
Speaking after inspecting the restaurant, microbiologist Yuen Kwok-yung revealed that the Cathay Pacific aircrew member who is thought to be the index case in the cluster had a headache and diarrhoea when he ate there.
“This index case who has been sitting there for more than one and a half hours may be shedding a lot of virus and this virus is being carried by the air current through the crevices in the partitions of all those smaller rooms and also trapped at the corners where air stagnation occurred,” he said.
“That’s why the other customers in this restaurant were infected.”
Health authorities on Tuesday reported 39 newly confirmed Covid cases, 26 of them asymptomatic.
Twelve more patients were found to be infected with the Omicron variant, bringing Hong Kong’s total to 114.
Last updated: 2022-01-04 HKT 21:35