- The model developed by Hong Kong University suggests coronavirus outbreak worse than officially reported
- Model, which used travel and other data to map out the likely spread of the virus, estimated 1,343 people had been infected in Wuhan
The Wuhan coronavirus has already spread to 20 other cities in China, according to a study from the University of Hong Kong that suggests the outbreak is worse than officially reported.
A model developed by HKU's infectious disease experts found the virus would have taken hold across swathes of mainland China between January 1 and 17.
The analysis by the university's WHO Collaborating Centre for Infectious Disease Epidemiology and Control was unveiled on Tuesday, when health authorities reported 21 cases in six mainland cities other than Wuhan, the source of the outbreak.
HKU's model, which used travel and other data to map out the likely spread of the virus, estimated 1,343 people had been infected in Wuhan, along with 116 in 20 other Chinese cities.
Hong Kong, with no confirmed cases, was not among the affected cities, according to the study.
By Tuesday, 291 confirmed cases of the newly discovered virus had been officially confirmed on the mainland. Of those, 270 cases were from Hubei province, where the virus' epicentre was located, and 21 cases recorded in six other cities " Beijing, Shanghai and four in Guangdong province.
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Thailand, Japan and South Korea have also recorded a total of four cases. There have been four deaths attributed to the Wuhan coronavirus overall.
The medical centre at HKU also found at least 10 new cases would surface in five major cities across the mainland by January 31, the seventh day of the Lunar New Year.
That conservative estimate for Beijing, Shanghai, Chongqing, Guangzhou and Shenzhen was based on assumptions that the force of infection subsides, there is only one source of the outbreak and the absence of super-spreading, where an infected person transmits to an unusually large number of people.
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Professor Gabriel Leung, founding director of the infectious disease centre, said health authorities could use these figures to check whether they were identifying all the cases in their jurisdictions.
"If you were the local health authorities in any of these places, these are the numbers you would be expecting to confirm in your tests," he said.
Leung's team worked out the estimated number of cases in Wuhan based on the four cases exported overseas.
The Wuhan figure was then used to predict the number of cases that had spread from the city in Hubei province to other parts of China.
Factors taken into account included the number of travellers by air, train and road from Wuhan to other mainland cities during the mass movement of people for the Lunar New Year in 2019 and projections for this year between January 10 and February 18.
But the model was based on a number of assumptions, some of which were conservative, including that Wuhan remained the only source of the disease, there was no super-spreading of the virus, the force of infection reduced by 75 per cent and that cases were detected effectively.
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It estimated Beijing, Shanghai, Chongqing, Guangzhou and Shenzhen would each see two cases from Wuhan during the weeks before and after the start of Lunar New Year, which begins on January 25.
Leung urged the public not to panic but said all health authorities involved should stay on high alert.
Meanwhile, Hong Kong's acting chief executive Matthew Cheung Kin-chung said on Tuesday morning the government was prepared for the worst-case scenarios associated with the virus transmitting between humans.
Additional reporting by Alvin Lum
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