“Hong Kong is now facing a severe situation,” he told a radio programme. “Some citizens have let their guards down on keeping personal hygiene as the pandemic has entered the third month – the situation is becoming a little out of control.”

He said up to 100,000 people had returned to Hong Kong, mostly from Europe or the US, before the government’s 14-day mandatory quarantine measure came into effect on March 19. As most of them were not tested for the virus, many transmission chains could have already appeared.

Yuen suggested if the daily surge continues, coronavirus patients with mild or no symptoms could be sent to quarantine facilities to reduce the pressure on the health care system.

“For those infected young people who have only mild symptoms, such as having only a sore throat or runny nose without any fever, they could be placed in quarantine facilities like Chun Yeung Estate [in Fo Tan],” Yuen said. “They won’t need treatment by medical workers. They can even return home for further self-quarantine after their viral loads are lowered.”

He added that a patient usually develops antibodies about seven to 10 days after being infected. If a patient has no symptoms and a low viral load, he believes the risk of transmission is small.

“If we had unlimited resources, of course the best thing to do is to isolate all patients [in hospitals]. But we do not have unlimited resources, that’s why we need to find other ways forward,” Yuen said, adding a balance should be struck that acknowledges the city’s limited resources.

The Hospital Authority’s Tony Ko said if cases continued to surge by dozens per day, the health care system could face huge pressure in providing isolation beds despite the addition of 400 isolation beds at Hong Kong hospitals this week.

As of Sunday, the occupancy rate of the city’s 1,012 isolation beds and 534 wards stood at 62 per cent and 74 per cent, respectively. The Hospital Authority has earlier conceded that some patients have experienced longer waits before being admitted to hospitals.

“Depending on the development of the pandemic. If it develops stably [in Hong Kong], we should still be able to handle that. But if infected cases surge in the rate like in the US or in Europe, we might have to consider altering our strategies,” Ko told the same radio programme.

“Those patients whose conditions are mild or who have recovered more rapidly might be discharged from hospitals and be quarantined in the community,” he said.

Ko added that health authorities would continue to look into adding more isolation beds in hospitals but warned the move might not be sustainable, as new isolation units had to be converted from ordinary wards.

“Our resources should be reserved for the more severe Covid-19 cases,” he said. “If there are up to 50 or 60 new cases every day, our isolation beds would be quickly filled up … By merely adding beds in hospitals, that would not be a sustainable measure.”

Another health expert at HKU, leading microbiologist Ho Pak-leung, also agreed patients with mild symptoms or asymptomatic could be discharged and be moved to quarantine facilities, but said they should not return home until testing negative for the virus.

“Patients who still have their stool, sputum or other samples test positive should not be allowed to return home … as they could still infect others [living there],” Ho said.

“Some people who should be under mandatory home quarantine have previously flouted the rules by going out onto the streets. If patients who are still testing positive can return home, who knows if a similar situation could occur?”

Ho also urged the government to legislate a mandatory requirement for everyone to wear masks to prevent the disease from further spreading.