The deadly new coronavirus outbreak that started in the central Chinese city of Wuhan has entered the stage of transmission among families and hospitals, taking it a step closer to a full-blown community epidemic, according to a top expert in Hong Kong.
The warning came on Tuesday, as a study by the University of Hong Kong estimated that the virus had already spread to 20 other mainland cities from Wuhan in Hubei province between January 1 and 17, suggesting the situation was worse than officially reported.
Professor Yuen Kwok-yung, a top infectious diseases expert at the university, said the transmission of the coronavirus had entered its "third wave."
"Now we can see infections of family members and in hospitals. What we are worried most about is a large outbreak in the community that may cause a situation like what we experienced during Sars," Yuen said, referring to the severe acute respiratory syndrome pandemic of 2002-03.
"We are worried that the super-spreading event might have occurred already … we need to see if sustained human-to-human transmission has happened."
The renowned microbiologist, just back in Hong Kong after a fact-finding trip to Wuhan, called for more measures to tackle the ballooning crisis and curb the spread of the virus.
On Wednesday, Gao Fu, director-general of China's Center for Disease Control and Prevention, said that the virus, which has sickened over 400 people across the country and led to nine deaths, originated from the wild animals sold at a seafood market in Wuhan. Gao warned that a major challenge was that the new strain was adapting and mutating.
The crisis could not have come at a worse time, as the Lunar New Year holiday sees the biggest mass migration of people on the planet, with hundreds of millions of Chinese workers in cities returning to their rural homes.
So far, all of the deaths were reported in the Chinese province where the virus first appeared. The government is now enforcing stricter quarantine measures to try and contain the infections.
The virus, which has pneumonia-like symptoms, has been found in Taiwan, the United States and three other Asian countries, with most of the cases involving people traveling from Wuhan.
In China, the National Health Commission will authorize medical institutions to quarantine all patients and people in close contact with them as a prevention and control measure, Li Bin, deputy director of the commission, said on Wednesday.
"The virus is mainly transmitted through the respiratory tract," Li said. "It may mutate and there is risk of further spread.
"Now, during Chinese New Year, the surge (in people moving around the country) increases the risk of the epidemic's spread and the difficulty of prevention and control. We must not take it lightly."
On Tuesday, the commission upgraded the coronavirus to a Class B infectious disease but said it would use the stricter control measures for a Class A disease to handle the outbreak, meaning any infection nationwide must be reported within two hours and monitored.
A Class B classification gives the government the power to stop travel to, from and within a city, and to take other emergency measures that would effectively shut down a city.
Closing down a city the size of Wuhan, with a population of 11 million people " more than New York City " would be unprecedented in China. Such a measure would also come with hundreds of millions of people traveling this week for the start of the Lunar New Year holiday.
China's top infectious disease expert, Zhong Nanshan, said quarantine was the only way to stop the disease at present.
"As soon as it spreads from human to human, quarantine must be the first priority," Zhong said at a press conference on Tuesday. "At the moment, I don't think quarantine has been implemented thoroughly enough."
Zhong is leading a government-appointed task force to handle the outbreak. He said quarantine measures were the most effective because "at the moment there is no effective drug for treatment for this new strain of coronavirus."
Medical staff in Wuhan hospitals appeared to have borne the brunt of human-to-human transmissions of the disease.
According to a study published on Tuesday by a joint research team from the Chinese Academy of Sciences, the People's Liberation Army and Institut Pasteur of Shanghai, the new virus may share the same bat-related source as Sars. They said the strain was weaker than the devastating 2002-03 Sars outbreak but was still "highly infectious."
Additional reporting by Sarah Zheng and Stephen Chen.
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