Dr Sean Yuan Hsiang-yu, Assistant Professor in the Department of Biomedical Sciences at City University of Hong Kong (CityU), estimates that the worst-case scenario for a novel coronavirus outbreak in the local community could be more than 220 individuals infected over the next two weeks after the Chinese New Year holidays. He cited a joint research project between mainland China, Hong Kong and Taiwan universities and research institutes at a media briefing on 31 January.

After the holidays, a large number of Hong Kong residents will return to Hong Kong from the mainland. Assuming 200,000 people come back, any infected, but undiagnosed, individual can infect 2.92 persons (Note: 1). If an infected, but undiagnosed, individual has had the new virus for three days (including incubation time), the number of imported cases can increase to 7.1 persons, each of whom may further infect 20.7 persons, leading to a total of 27.8 infected individuals. Similarly, if that same person has had the virus for five days, the imported cases can increase to 15.4, and they may infect another 45 persons, which can bring the total number to 60.  If that infected individual remains undiagnosed for eight days, the imported cases can increase to 37.8, and they may infect 110.4 persons, which can bring the total number to 148.   

In the worst case scenario, if 300,000 persons return to Hong Kong from the mainland, it is estimated that 57 of them may be infected with the virus. If the infected individuals have had the virus for eight days, there will be 166 secondary infected cases in the next 2 weeks, which can bring the total number to over 220. 

As shown in the calculations above, Dr Yuan pointed out that early diagnosis and effective epidemic prevention measures can greatly reduce the risk of community outbreaks.

“The number of community infections confirmed in eight days is three times that of infections confirmed in three days. The government should minimise the risk of large-scale community outbreaks at the source,” he said.

Dr Yuan’s application to carry out research in the field of public health at CityU was approved by Professor Way Kuo, President of CityU, and an interview panel following a global recruitment drive by the Jockey Club College of Veterinary Medicine and Life Sciences, which was established in in 2018.

Before joining CityU, Dr Yuan was engaged in human genomic medicine research at the Institute of Biomedical Sciences, Academia Sinica, Taiwan, from 2003 to 2006. He then pursued a PhD in Biocomputing at Duke University, US. He has worked on predictive models of infectious diseases in the Department of Infectious Disease Epidemiology at Imperial College London in 2013 and he was engaged in dengue research at the National Health Research Institutes in Taiwan in 2017.