With Hong Kong preparing to quarantine anyone who crosses the border from mainland China, doctors and infectious disease experts are warning the territory's ability to protect itself from the coronavirus is about to be severely tested.

A steady stream of people passed through the arrivals area at the terminus of the Hong Kong-Zhuhai-Macau Bridge on Thursday, one of just two land crossing points still open. Several told CBC News they were leaving the mainland while they still could.

"I heard about the quarantine order yesterday, so I decided to come back [early]," said Irene Kwok, who lives in Zhuhai, right next to Macau, but wanted to get to Hong Kong to look after her mother.

Irene Kwok cut her trip to mainland China short to return to Hong Kong and avoid a 14-day quarantine. (Pascal Dumont/CBC)

"If we listen to the doctors, we wear face masks, wash our hands and have less gatherings, then we can be healthy," said another traveller, Anson Lee. While he agreed with the tough new entry measures, they also forced him to cut short his visit to the mainland.

On Wednesday, Hong Kong's government announced that as of Saturday, anyone — Hong Kong resident or otherwise — who arrives from China will have to spend the next 14 days in quarantine.

The decision marks a dramatic turning point in the city's fight against the coronavirus. Up until now, government leaders have insisted it was critical to keep the border open as much as possible for economic reasons.

Passengers arrive at the Hong Kong-Zhuhai-Macau Bridge in advance of Saturday's quarantine. (Pascal Dumont/CBC)

Dire predictions

The development that appears to have changed the equation may be the realization that in six new cases discovered this week in Hong Kong, none of the patients had any connection to Wuhan, China, the epicentre of the outbreak.

One of Hong Kong's most prominent infectious disease experts, Dr. Yuen Kwok-yung, told local media Thursday that he believes the coronavirus has passed a crucial threshold — that it has reached the status of a "community outbreak," as it appears transmission in up to six recent cases has occurred locally rather than people contracting the virus from someone who had visited China.

The total number of cases in Hong Kong — 22 confirmed positives, two suspected cases and one death — is modest compared to the almost 30,000 cases next door in China. But the count has moved up steadily every day.

Health care providers who deal in critical care say they are preparing for an arduous time in the days and weeks ahead.

Dr. Alfred Wong, a cardiologist at Hong Kong's Tuen Mun Hospital, told CBC News he will soon be part of a so-called "dirty team" tasked with treating coronavirus patients.

"All of us will be not only be working in the isolation wards, but also will be isolated from the rest of the world, our family, our friends, in order to decrease the chances of bringing the virus to the public," he said in an interview at the hospital.

Cases of coronavirus in Hong Kong are rising by the day, with 22 confirmed positives and two suspected cases as of last count. (Pascal Dumont/CBC)

Wong later posted a photo on Facebook of him having dinner with his wife, her sitting at the far end of the table, keeping her distance. "You can imagine all the emotions," he told CBC.

Wong's dire prediction for the next 14 days echoes Yuen's.

"It is almost for sure that we are facing a catastrophe here in Hong Kong," Wong said.

'Panic buying'

While there are few signs of outright panic in Hong Kong, it's clear there is a great deal of anxiety. At a pharmacy in the shopping district of Mong Kok on Thursday, a pack of 10 face masks was selling for $12 Cdn — roughly six times the regular price.

"The number of confirmed patients is on the rise, and there is a death case, so people are very worried, which leads to panic buying," said shop worker Michael Jung. He said with the quarantine of people coming in from China, prices are only bound to go up.

Up to 7,000 Hong Kong health care workers have been staging rotating strikes this week, pushing for a tougher government response to the coronavirus. (Pascal Dumont/CBC)

"When China's supply is dropped, the supply [in Hong Kong] falls immediately and people become crazy," said Jung.

On Wednesday, an estimated 10,000 people joined a lineup that stretched several blocks through a Kowloon neighbourhood after a supplier announced they would make 500,000 masks available at low prices.

Social media websites have been full of photographs of store shelves emptied by people stocking up on toilet paper and other cleaning supplies for their homes in case they can't go out for a while.

Old anxieties

Time and again, when CBC spoke to people about their anxieties over the coronavirus, they cited the example of SARS 17 years ago.

Like this new coronavirus, SARS originated in China and crossed the border to ravage Hong Kong. By the time it had run its course, 1,700 people in the territory had been infected and 300 had died.

The epicentre of that outbreak was the high-rise complex of Amoy Gardens in Kowloon's Jordan Valley area. Health authorities believe a Chinese man visiting his brother brought the virus with him, and that it was passed throughout this densely packed group of towers and sickened people via faulty sewage pipes.

Memories of the 2003 SARS crisis haunt Hong Kong resident Wilson Yip. (Pascal Dumont/CBC)

Resident Wilson Yip was a local council member at the time, and said the latest coronavirus worries him even more, because it appears to be affecting many more people.

"I think this may end up being more [dangerous] than SARS," he said, standing next to Block E, one of the buildings that was evacuated back in 2003.

He said that at the time, face masks were difficult to come by and few people took the issue of good hygiene seriously. Whereas now, practically everyone on the street or in a public place has covered their face.

Yip said he's encouraged by the decision of China's government to quarantine the city of Wuhan, as well as measures undertaken by Hong Kong's administration to effectively restrict border crossings to all but emergency travel.

"I have more confidence. Both the government and citizens are quite aware compared to 17 years before," said Yip.

Politically divided

Politically, however, Hong Kong remains deeply divided over its response to the outbreak.

The city was already polarized after months of anti-government protests over the summer and fall against the administration of Carrie Lam, and what critics saw as overreach by the Chinese government.

While the black masks of the street protesters have been put away for the moment, Hong Kong's health care workers have filled the void with rotating strikes and daily picket lines, calling for Lam to totally seal off the territory.

In 2003, an outbreak of SARS in the Hong Kong neighbourhood of Amoy Gardens sickened hundreds. (Corinne Seminoff/CBC)

The announcement about the quarantines has been seen as too little, too late.

Alfred Wong, the cardiologist, who supports the striking health care workers, argued the only way Hong Kong will get through the coronavirus crisis is to seal itself off completely from its giant neighbour.

"This is a question of all or nothing," he said. "If you closed down some [border crossings] and leave others open, I mean, basically you just leave the border open."