China’s symptom-free coronavirus carriers raise infection worry
SHANGHAI: The number of new coronavirus cases in China totalled 47 on Tuesday - down from 78 a day earlier - the National Health Commission said, and all were travellers returning home.
The total number of confirmed cases in China hit 81,218, with 474 imported infections at the end of Tuesday. The death toll in China reached 3,281 as of the end of Tuesday, up by four from Monday.
The falling number and lack of local transmissions led to the opening of the Hubei province border yesterday after a two-month shutdown. The province was the epicentre of the virus.
But the existence of a substantial but unknown number of asymptomatic carriers of the coronavirus in China has raised concerns that people could still be spreading Covid-19 without knowing they are sick.
Asymptomatic cases present a huge challenge in the control of infectious disease, making it harder to detect and stop transmission.
In China, the number of known asymptomatic cases is classified, and it is not included in the official data, though the South China Morning Post, citing unpublished official documents, recently said it was more than 40,000.
Asymptomatic cases are currently found through "contact tracing". China identifies people exposed to someone with a confirmed diagnosis, and if they test positive, they are quarantined whether or not they manifest symptoms.
"Asymptomatic patients have all been discovered during our contact tracing," said Dr Wu Zunyou of the China Centre for Disease Control and Prevention at a briefing on Tuesday.
"So will they be able to create transmission? They won't."
Still, the failure to include them in the official data has raised concerns about Beijing's commitment to transparency, and some experts say it could also create a misleading picture about how the epidemic spreads and whether or not it is under control.
Some experts warn that undetected, asymptomatic patients could create fresh transmission routes once lockdowns are eased. But it is also unclear how much they might infect others. - REUTERS