Coronavirus: more asymptomatic carriers reported in China, but experts disagree on the threat they pose
- Although people who don’t show symptoms are ‘very infective’, there’s probably not very many of them, respiratory disease expert Zhong Nanshan says
- But head of specialist Covid-19 team in Shanghai says asymptomatic carriers ‘now pose the biggest risk’ in terms of preventing imported cases
Two of the doctor’s colleagues in Henan, neither of whom had worked in Wuhan, also tested positive, officials said.
The news sparked alarm on social media.
“No symptoms is so horrible,” a person said on Weibo, China’s Twitter-like platform. “It’s impossible to prevent it effectively. I hope the government can make the number of asymptomatic cases public.”
As of Sunday, there had been more than 670,000 confirmed cases around the world and close to 32,000 deaths.
In China, which was the initial focus of the pandemic, the number of local infections has slowed almost to a halt, but the country continues to battle the threat of imported cases.
Zhong Nanshan, one of China’s leading respiratory disease specialists, said in an interview with state broadcaster CGTN on Sunday that although asymptomatic virus carriers were “very infective because there is very high viral load in their upper respiratory tracts”, he did not think there were many of them.
“Right now … the fatality rate is only 0.9 or 1 per cent,” he said. “I suppose we don’t have too many asymptomatic patients. If we did, they would be transmitting [the virus] to other people and pushing the number [of confirmed cases] higher.
“But now, it’s actually going down, and in some provinces to close to zero. I don’t think that’s a big problem.”
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But not everyone is as optimistic as Zhong.
“Asymptomatic coronavirus carriers usually have strong immunity and show no symptoms for more than two weeks despite being infected,” he said.
“If they return home from abroad and are not isolated in a timely fashion or are released too soon from their two-week quarantine, they pose a great risk of community infection.”
Wang Xinhua, president of Guangzhou Medical University, said it was still too early to say what threat asymptomatic carriers posed.
“Confirmed cases with no symptoms do exist, but we don’t know the specific number and the workings and characteristics of this [type of] carriage are not clear,” he said.
“I think [in such people] the viral load is low and the virulence is weakened. If not, they would show symptoms.”
What was important was for the government to focus its prevention and control measures in the right areas, Wang said.
“Anyone who has had close contact with an infected area or patient should be tested and isolated, but we don’t have to test everyone. That’s too much work and there is no need,” he said.
“Tackling the asymptomatic and imported cases is the most important task.”
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