South Korea and China have reported fresh surges in coronavirus cases in the wake of both countries easing their lockdown measures.
"The nation is at risk," Park Won-soon, the mayor of the South Korean capital Seoul, said yesterday, warning that the next few days would be "critical" in preventing the spread of the virus from a cluster of cases linked to several nightclubs and bars.
A total of 86 new infections have been reported in the latest outbreak, as officials race to track down thousands of people who may have come into contact with a 29-year-old man who visited the venues before testing positive for Covid-19.
South Korea has won global praise for successfully controlling the virus with its efficient "test, track, treat" strategy, reducing new infections to a daily trickle of single-digit figures. The sudden spike in cases has raised fears of a second coronavirus wave.
The authorities have tested more than 2,450 people who went to the night spots in the Itaewon neighbourhood, but officials are still trying to track down about 3,000 more with the help of phone records and credit card data.
Entertainment venues require customers to provide their contact details at the entrance for tracing purposes in the event of an outbreak.
However, Mr Park said he believed some who were not accounted for may have given false details.
The contact tracing operation has been complicated by the fact that many of the new cases have been linked to venues catering to members of the LGBT community.
Homosexuality is often treated as a taboo subject in South Korea's conservative society, and LGBT people can face discrimination, including job losses and hate speech.
The new cluster has highlighted difficulties with the country's invasive tracing methods and its disclosure of some patient information, including their recent locations.
The authorities have sought to reassure those who come forward that their privacy will be protected.
Asia's fourth largest economy was just starting to loosen work-from-home precautions and is due to reopen schools in phases from this week. This is still set to go ahead, although the government has cautioned it could be reversed if the disease spreads.
On Sunday, Moon Jae-in, the president of South Korea, asked citizens to neither panic nor let down their guard, but warned that the country was in a "prolonged war" against the virus.
New cases reported yesterday in the Chinese city of Wuhan, where the pandemic began, also offered another worrying twist.
After a severe 76-day lockdown, Wuhan, a city of 11 million, had only begun to return to relative normality late last month, but yesterday it announced a new cluster of five cases - all people who had been infected locally.
The ability of the disease to spread undetected in such a heavily surveilled city raises concerns about the prospects for a quick return to normality.
Over the weekend, China was also forced to impose a new lockdown on Shulan, a city of 700,000 in the north-eastern province of Jilin bordering North Korea.
The new restrictions have raised suspicions about a coronavirus outbreak in the isolated country.
North Korea's claims to have zero cases of infection have been met with scepticism, amid concerns that the impoverished nation would not be able to cope with a national epidemic. (© Daily Telegraph, London)