Sunday’s tally included 34 tied to a cluster at Kwai Tsing, where 29 workers or their family members had previously been reported infected, taking the tally linked to the site to 63 cases.

Thirty-three of the 34 infected, most of whom exhibited no symptoms, were linked to the Wang Kee Port Operation Services Limited site and identified after testing bottles were distributed.

The infected workers primarily worked outdoors unloading, handling or inspecting containers, while some part-time workers also helped to move and arrange goods, though preliminary investigations found shared employee facilities to be the likeliest source of infection.

“More than a hundred staff working for Wang Kee use the same common area. [They] eat, relax, shower inside, sleep over and live like a family. That would contribute to the high transmission,” said Chuang, head of the centre’s communicable disease branch.

Situated near Kwai Chung and Tsing Yi, the affected container site contains nine terminals, and 24 berths operated by five different operators. Each operator further subcontracts businesses to local companies such as Wang Kee.

Concerns were also raised about the potential for a bigger outbreak given that workers from different companies may have had contact with containers handled by Wang Kee staff, while some would have been taken aboard ship and handled by foreign seafarers.

More than 10 subcontracted companies in the terminal have each had at least a few employees test positive for the coronavirus so far, but Wang Kee appeared to be the most high-risk.

“We encouraged the company to fully sanitise the area, and to minimise or suspend business for a period of time, if that’s possible,” Chuang said. “We hope we can contain the outbreak from this cluster soon.”

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Health officials have so far distributed about 4,000 testing bottles at the site, with another 4,000 to follow soon.

The Post has contacted Wang Kee seeking comment.

Wong Yu-loy, of the Confederation of Trade Unions, said he believed the packed dormitory accommodation was to blame for the breakout.

“The so-called dormitory is converted from containers only. They install lights and air-conditioning and that is it. Not even a window. You can imagine it as a big black box with electricity and water supply. Depending on the size of the container, sometimes they will put about 10 bunk beds in it.”

Wong said logistics workers, such as those working for Wang Kee, often worked 16-hour shifts, spending as long as three to four hours a day in the makeshift break areas.

“Some will take a nap, some will take a shower. We are talking about 10 or more people in one container-size dorm at the same time. It is packed and does not offer the space to allow for social distancing. Once one is infected, others can also easily catch the virus,” he said.

Jessie Chung Wai-yin, chairwoman of the Hong Kong Container Terminal Operators Association, who declined to comment on the condition of the workers’ quarters, said operators had been meeting with the government to discuss ways to stop the virus’ spread.

“The last thing we want to see is that the port has to be shut down. It doesn’t concern only the container terminals, it concerns the entirety of Hong Kong,” Chung said.

She added that according to her understanding, another “clean” contractor had been hired to take over Wang Kee’s work for the moment.

“So, there will not be any impact on the operation of the port,” she said, noting Wang Kee was only “one of many” contractors working at the port.

Willy Lin Sun-mo, chairman of the Hong Kong Shippers’ Council and a member of the government’s Logistics Development Council, said: “I believe that at this moment, the impact [on the operation of the Kwai Chung container port] is minimal. If needed, the containers could easily be handled via Shenzhen. If you recall the strike of several years ago, there was no impact to import and export, in my personal view.”

Professor David Hui Shu-cheong, a government public health adviser, said as some of the workers may have come into contact with seafarers, authorities should look into whether those working aboard ships played a role in transmitting the virus.

A cluster linked to Indonesian domestic workers, meanwhile, also continued to grow, with one additional maid living on the second floor of a boarding house at Cheung Hing Mansion in Mong Kok testing positive.

Another maid living on a different floor of the same building had previously been confirmed infected. Both accommodation are run by the same owner, who had a family member among Sunday’s new cases.

“The owner is quite uncooperative, and has refused to provide residents’ details,” Chuang said, adding they believed the maids had found the flats through online advertisements, and moved in shortly after paying.

In light of the growing cluster, Chuang said they would distribute testing bottles to all residents of the building, while the four women living in the same unit on the second floor would be sent to quarantine facilities.

Others to be sent to quarantine camps included about 20 Kowloon Dairy delivery workers, who earlier shared a company truck with a 58-year-old staff member confirmed to have the coronavirus on Saturday.

It has been more than one month since Hong Kong imposed its toughest social-distancing measures yet against the virus, including limiting public gatherings to two people, and banning nighttime dine-in services at restaurants.

Henry Yeung Chiu-fat, president of the Hong Kong Doctors Union, said the government had sent it an email inviting medical staff from private clinics, including dental clinics, to help with the universal and voluntary Covid-19 testing programme.

They are expected to reply on or before Wednesday.

“The universal testing is expected to begin on August 24 for two weeks,” Yeung said. “There will be swabbing stations in place across Hong Kong’s 18 districts. Private doctors, nurses and dentists are being invited to help take samples from those who don’t know how.”

Yeung said the government planned to hire about 2,000 private medical staff, and said swabbing stations would be set up in open spaces, including in shopping centres, playgrounds, and large community centres.

“The sample taking won’t be conducted at private clinics to avoid cross infections,” he said.

Yeung expected up to a thousand private medical staff would take part in the screening exercise, and said they would be paid between HK$300 and HK$800 per hour, with surgical masks and gloves provided.

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“But I think the government should also provide special insurance coverage for them, and extra medical gear such as face shields and protective gowns as the task of taking samples is very high risk,” he said.

Meanwhile, Dr Linda Yu Wai-ling, a chief manager for the Hospital Authority, responded to demands for better protection for frontline medical workers from the Hong Kong Medical and Health Care Staff General Union.

The union on Saturday said the personal protective equipment being provided to medical staff had declined in quality, while also urging the Hospital Authority to expand a subsidy given to frontline workers to help pay for temporary accommodation necessary after high-risk shifts with Covid-19 patients.

“The Hospital Authority has clear standards for the type of protective gear used based on professional opinions and overseas guidelines,” Yu said. She added there was enough protective gear for the next four months and all employees were able to access necessary equipment.

She also said staff would be assigned to work in high-risk wards for 14 days continuously so they could qualify for the subsidy, which requires workers to spend more than two-thirds of a month working in high-risk areas.

Additional reporting by Elizabeth Cheung