Zhong believed it could be done now. “I think Hong Kong and the mainland should also take this step and have a mutually recognised [system] … I don’t think it’s that essential to be isolated in Hong Kong for 14 days,” he said. “That’s because Hong Kong is facing a big economic problem.”

The city’s economy slumped 8.9 per cent year on year in the first quarter, its worst contraction on record.

But in the interview, he argued the return to schools and workplaces in Guangdong and across the country had not caused huge problems, saying “it appears possible to cross the river by feeling the stones”.

About 60 per cent of the confirmed infections in Hong Kong were either imported cases of people infected elsewhere, or their close contacts. Of the Hong Kong cases, 20 had travelled to the mainland during the incubation period of the disease.

Since May 10, Macau and the neighbouring mainland city of Zhuhai have recognised each other’s health code system, to determine if individuals crossing the border ought to be in quarantine or free to move around.

The system generates coloured QR codes to indicate a person’s level of risk based on their health, contact with Covid-19 patients and travel history.

Even before second wave, countries could face ‘second peak’, WHO warns

A green code means the person is well and not related to any Covid-19 cases, while red indicates infection, suspected infection or that a close contact is a confirmed case. Yellow means the person had a fever or respiratory symptoms.

With growth rates of Covid-19 cases locally and in neighbouring cities slowing and Hong Kong’s compulsory quarantine for arrivals from the mainland, Macau and Taiwan set to expire on June 7, the health secretary had said proposals for relaxation were looked at but no date had been fixed.

The life or death question: who gets the Covid-19 vaccine?

In the interview, Zhong also praised Hong Kong’s efforts to defeat the virus, singling out its aggressive “suppression strategy” such as social distancing and mask-wearing policies.

“These are done very well, at around the same time or possibly even earlier than those on the mainland. [The enforcements] are also more stable.”

He added the city had also contributed to the battle by discovering “early and very key evidence” of human-to-human transmission of the coronavirus, citing a study by the University of Hong Kong that found infections had spread in a family cluster of six who had been to Wuhan, except for one who wore masks throughout the trip.

05:26

Coronavirus spread would dramatically drop if 80% of a population wore masks, AI researcher says

Coronavirus spread would dramatically drop if 80% of a population wore masks, AI researcher says

Other achievements, he said, included the use of deep throat saliva tests rather than just relying on nasal swabs, as well as effective clinical treatment, which centred on using a cocktail of drugs.

Hong Kong in March imposed social-distancing measures at the peak of the pandemic, including capping the number of people joining public gatherings at four and closing bars, party venues and cinemas. The cap was relaxed to eight people this month as local infections dwindled.

The Sars outbreak claimed 299 lives in Hong Kong in 2003, with super spreading events such as large cluster outbreaks in the Amoy Gardens housing estate in Kowloon.

Additional reporting by Elizabeth Cheung

Read more form this series, part two, on the high number of fatalities in the US, part three, about how the blame game is affecting international scientific cooperation, and part four on the low risk of a coronavirus second wave.