Hong Kong recorded 70 new Covid-19 cases on Thursday as an outbreak in the old, densely populated Yau Tsim Mong district continued to worsen, with a coronavirus case also uncovered in a home for the elderly within a designated testing area. Around half of the 63 locally transmitted cases were in the district, including one in a smaller core area where testing was ordered for residents in all buildings. Sixteen infections were untraceable. The remaining seven cases were imported, including three people from Britain who had been in Dubai for a month before flying into the city through Singapore. Since December 22, Hong Kong has banned travellers who had been in Britain for a minimum of two hours in the previous 21 days, after a much more transmissible variant of the virus emerged. More than 40 people tested preliminary-positive, awaiting confirmation. Two scientific committees advised the government to prioritise Covid-19 vaccinations for four high-risk groups: residents and staff of residential care homes for the elderly and the disabled; health care workers; people aged 60 or above; and chronically ill patients aged between 16 and 59. The city’s overall tally of cases stood at 9,867, with 167 related deaths. The latest fatality was a 74-year-old woman with a chronic illness who died in Caritas Medical Centre on Thursday afternoon. An 80-year-old resident of a care home on Battery Street in Yau Ma Tei tested preliminary-positive, health authorities revealed. The man did not leave the home but could walk about freely and did not wear a mask at all times. Twenty-one residents and six staff members were identified as close contacts and would be sent to quarantine. “The exact source of infection in the elderly care home is still being investigated. If he did not go out of the home, it’s possible that other residents or staff infected him,” said Dr Chuang Shuk-kwan, head of the Centre for Health Protection’s communicable disease branch. Mandatory screening orders were issued for two more buildings, 121 Woosung Street and 7-10 Ferry Street, in the designated area – where a single infection triggers testing. Outside the zone, compulsory testing orders will be issued at Tak Yam House at On Yam Estate in Kwai Chung, Laguna City Block 5, and Prosperous Garden Block 2 in Yau Ma Tei, after infections were recorded in at least two flats. The precise mapping and placement of devices is more complicated this time, as there are many old pipes packed together in a densely populated neighbourhood HKU’s Professor Gabriel Leung Meanwhile, the Hospital Authority warned staff to refrain from sharing meals or gathering after several nurses at different hospitals were infected. A nurse from Queen Elizabeth Hospital tested preliminary-positive after eating with an infected colleague from North District Hospital. She also had meals with five other nurses and one clerical officer from Queen Elizabeth. At Princess Margaret Hospital, a nurse tested preliminary-positive after developing symptoms on Monday. She had a meal with a colleague, with a partition in between them. The woman was issued a quarantine notice on Saturday. No patients are listed as close contacts. Across Yau Tsim Mong, sewage testing devices have been installed in a bid to identify potential new outbreaks. Professor Gabriel Leung, dean of the University of Hong Kong’s faculty of medicine, said researchers had shifted the focus of their sewage surveillance network from public housing in East Kowloon to Yau Tsim Mong, where outbreaks among subdivided flats in the area continued to grow. He said all of the city’s 28 sewage testing devices have been moved to the area, where stringent mandatory testing requirements had been in place since late last week. Haphazardly built plumbing systems and poor ventilation in subdivided units in old tenement blocks have been a perennial problem across the city, and identified as a possible path of virus transmission. The sewage pilot scheme, developed by an HKU team, helps detect hidden carriers through samples collected from building pipes. It identified the first evidence of sustained positive results from a public housing block last month, prompting a mandatory testing order for residents and visitors there. Leung also revealed the team would run a second round of tests in Yau Tsim Mong after mandatory screening was completed to see if any residual virus carriers remained there. Neighbouring Sham Shui Po, another area recently zoned for mandatory testing, could be next, he added. “The precise mapping and placement of devices is more complicated this time, as there are many old pipes packed together in a densely populated neighbourhood full of tenement buildings,” the health expert said. Separately, Professor Yuen Kwok-yung, a HKU microbiologist advising the government, will investigate false negative results involving a Nepalese family who live in Yau Tsim Mong, a government source said. Dilip Rai revealed on his Facebook page that he had developed a sore throat on January 9 and a fever on January 12. He tested negative at a community testing centre on January 15 and again at a mobile testing station on January 18, only to test positive later that day after admission to Kwong Wah Hospital. His wife and son were tested on Monday but returned negative test results. They were sent to Penny’s Bay for quarantine where they later tested positive for the coronavirus. Additional reporting Victor Ting