Infectious disease control: the battle to beat coronaviruses

16 April 2020

For Professor Joseph J Y Sung, it was very much a case of deja vu. After 17 years, a Severe Acute Respiratory Syndrome-CoronaVirus (SARS-CoV) has returned as SARS-CoV-2, bringing back memories of when the Prince of Wales Hospital in Shatin was the epicentre of the first SARS outbreak that shut down Hong Kong for three months.

In the spring of 2003, the atypical pneumonia spread from the first local contact patient admitted to the hospital with SARS symptoms – to other patients in Ward 8A, their families and around 100 medical workers. By mid-July, 298 people had lost their lives there and in other hospitals across the city.

Sung (Croucher Senior Medical Research Fellowship 2004, Croucher Fellowship 1988), a leading gastroenterologist, was Chairman of the Department of Medicine and Therapeutics at the hospital at the time, and led the fight to save the lives of waves of critically ill patients, for which he was lauded as an “Asian Hero” by Time magazine.

That experience prompted him to want to learn more about infectious disease control. He received a Croucher Medical Research Fellowship to spend three months at Johns Hopkins University, Bloomberg School of Public Health, for this purpose, and to share how Hong Kong had managed the SARS fight.

On his return in 2004, Sung, who went on to become Chinese University of Hong Kong’s vice-chancellor and is now Mok Hing Yiu Professor of Medicine, in the Department of Medicine and Therapeutics, established the Stanley Ho Centre for Emerging Infectious Diseases as its founding director.

The centre, now directed by Professor David Hui, is fighting against COVID-19 with its ground-breaking research. For example, Professor Paul Kay Sheung Chan, the centre’s deputy director, was the first to isolate the CoV-2 virus in the stools of patients who had recovered from the disease.

The study Chan led involved the analysis of more than 300 specimens from 14 Hong Kong patients confirmed with COVID-19. The team analysed specimens including sputum, nasopharyngeal swabs, deep throat saliva, blood, urine and stools. They discovered that the virus was detectable in the faecal samples of all patients, regardless of the degree of illness.

In addition, three patients still had viruses in their stool samples even when no longer found in the other samples, suggesting that virus shedding in stools is common and could provide an alternative screening tool. The study also highlighted the potential risk of environmental contamination.

Other findings showed that sputum had the highest amount of coronavirus (more than 300 times that found in deep throat saliva), the virus load in stools was comparable to deep throat saliva, and all urine samples were negative.

This research enabled the centre to raise the alert in March 2020 that the virus does not only spread through respiratory droplets, but that excreta, particularly the stool, could also be a source of infection, and that people can have diarrhoea, without respiratory systems, and be missed in diagnosis.

In light of these results, the team has now set out to screen stools and saliva for 100 asymptomatic close contacts admitted to Hong Kong quarantine centres to help determine whether stool tests can effectively detect COVID-19 in asymptomatic people. The team has also gone on to develop stool tests, now adopted by Hong Kong’s Department of Health to identify the disease among asymptomatic children arriving in Hong Kong.

Sung said that the centre has also played an important training role for infectious disease and epidemiology, greatly expanding the number of experts now working in hospitals across Hong Kong compared with 2003.

Meanwhile, much of the research conducted at the centre is happening in collaboration with Mainland China scientists, where there is also a new generation of infectious disease experts and many researchers with publications in leading international journals.

While SARS CoV-2 is similar to its predecessor, Sung noted important differences. This time, Hong Kong has not been at the epicentre of the disease where, until late March, there had been relatively few cases. “I think Hong Kong has learnt a hard lesson from 2003,” he said, adding that people in the city had become highly cautious and alert. From day one there had been widespread use of masks, frequent washing of hands, and efforts to minimise social gatherings. “That accounts for our early success,” he said.

However, the city could not be complacent as numbers had been on the rise recently. He pointed out that the scale was much larger than SARS this time – the 2003 epidemic affected a total of around 8,000 globally. In addition, some people carried the disease without symptoms, while greater global connectivity had increased its transmission.

He also described claims that COVID-19 is no more serious than influenza, and that people could get used to it, to be an “optimistic view” because the death rate was still much higher than for influenza, while the number of cases was already overwhelming health systems. (Globally, the mortality rate among reported COVID-19 cases has been about 3.4 per cent, compared with much fewer than one per cent of those infected with influenza, according to the World Health Organisation).

Sung’s insights from SARS lead him to conclude that the best line of defence has to be to take all necessary measures to contain the virus to minimise the number of cases. “Once the number of cases exceeds a certain level, your health system can’t cope. Your mortality rate goes up because people needing hospital beds can’t get them, and people who need a ventilator can’t get into an ICU [intensive care unit].

“The number is most important in my mind. The battle can only be won by stopping the infection from being imported from outside, or from spreading locally,” he said.

“Prevention of large-scale outbreaks is the only possible way out.” 

Professor Joseph J.Y. Sung is Mok Hing Yiu Professor of Medicine and President of the Chinese University of Hong Kong. He received his MB BS degree from The University of Hong Kong in 1983, and was conferred a PhD in biomedical sciences by the University of Calgary in 1992, and his MD by CUHK in 1997. Professor Sung holds fellowships from the Royal Colleges of Physicians of Edinburgh, Glasgow, London, Thailand and from the American College of Gastroenterology, the Royal Australian College of Physicians, the American Gastroenterological Association, the Hong Kong College of Physicians and the Hong Kong Academy of Medicine. He is an Academician of the Chinese Academy of Engineering of the People’s Republic of China. Professor Sung received his Croucher Fellowship in 1988 and Croucher Senior Medical Research Fellowship in 2004

To view Professor Sung’s Croucher profile, please click here