In an exclusive, wide-ranging interview with the Post, veteran Chinese infectious disease expert Zhong Nanshan discusses the origin of the new coronavirus, how Hong Kong has become a role model in containing Covid-19, why the United States has recorded a higher fatality rate than the city and how Asian countries should get prepared for a second wave of infections. In the first of a four-part series, Zhong urges the Hong Kong administration to revive the economy by easing border restrictions.

A mutually recognised health system between Hong Kong and mainland China could enable cross-boundary travellers to skip mandatory Covid-19 quarantine and allow further relaxation of border restrictions, top Chinese infectious disease expert Zhong Nanshan says.

In an exclusive interview with the Post, Zhong, dubbed a “Sars hero” by Chinese state media for his pivotal role in the country’s fight against the severe acute respiratory syndrome epidemic in 2002-03, also praised Hong Kong for its efforts to contain the new coronavirus and called for more cross-border interaction to reboot the city’s economy.

Zhong said he would visit Hong Kong for further exchanges in August.

“Hong Kong has done beautifully this time, totally different from how it did 17 years ago during Sars,” said Zhong, who now serves as director of the State Key Laboratory of Respiratory Disease. “[Relaxing quarantine] can be and should be done now.”

His comments came after Secretary for Food and Health Sophia Chan Siu-chee told the Post earlier this month that officials were studying proposals on using an electronic health certificate to exempt residents from the 14-day quarantine when they visited Macau and Guangdong province in a bid to create a “travel bubble” to make it easier for people to move between regions.

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.

The 83-year-old, who leads the National Health Commission task force investigating the coronavirus, in January visited the front line in Wuhan, where the virus was first reported. A regular voice of caution, he recently warned against a second wave of imported infections on the mainland as most people there did not have immunity.

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”.

Hong Kong on Monday reported no new coronavirus cases for the third day in a row, and has 1,065 infections to date, with four related deaths. Macau has 45 confirmed patients, and the mainland more than 83,300.

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.

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.

The Baltic countries of Estonia, Latvia and Lithuania recently began operating a similar common system and one has been floated for Australia and New Zealand.

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, Chan had said proposals for relaxation were looked at but no date had been fixed.

She hinted that easing would likely start with a “small number” of people, possibly those already exempted by local authorities for quarantine after arriving from the three places, including professionals, factory and business owners, students and truck drivers who frequently commuted across the border.

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.

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.