Shanghai residents are on a knife-edge as they fear being plunged back into a widespread lockdown after a lengthy stint under draconian restrictions earlier this year.
Millions in the mega city have undergone two rounds of compulsory testing as the city looks to quash new cases linked to illegal karaoke services.
Shanghai, which houses 26 million people, reported 54 new locally transmitted Covid cases for Wednesday, versus 24 the previous day. More than 70 cases confirmed in recent days are linked to the karaoke joints, authorities said.
China's commitment to its Covid-zero strategy is unwavering, with authorities taking no chances as more and more clusters emerge across the country.
Overall, mainland China reported 338 new local Covid cases for Wednesday, down from 353, with no new deaths, numbers that most countries would now consider insignificant.
But China's approach of rigorously stamping out outbreaks as they occur has residents wary of more of the kind of restrictions that have caused mental stress and financial hardship for many, disrupted global supply chains and overseas trade, and rattled financial markets.
Shanghai has only just emerged from a gruelling two-month lockdown which saw unprecedented resistance from residents rarely seen in the authoritarian nation.
Another 50 residential compounds and venues were locked down on Thursday in Shanghai, taking the total to 81.
"A resurgence of Omicron is not an issue in most other countries, but it remains a predominant issue for the Chinese economy," Nomura analysts wrote in a note, referring to the highly transmissible Covid variant.
As China is "by far the largest manufacturing centre in the world, any new waves of Omicron are likely to have a non-negligible impact", they added.
One case triggers measures for town
In Beijing, four new infections were reported, down from six the previous day.
The capital has mandated that from July 11 most people entering crowded venues, such as libraries, cinemas and gyms, will have to have been vaccinated.
After finding one Covid case involving someone who had arrived from Shanghai, the town of Xinjiang in the northern Shanxi province tested almost its entire 280,000 population, suspended taxis, ride hailing and bus services, and closed various entertainment venues.
In a different province, Shaanxi, which reported four new cases, the cultural and tourism authority requested travel agencies to cancel group tours in its capital Xian, famed for its Terracota Army.
China has justified its uncompromising coronavirus strategy by saying it is saving lives and is worth the "temporary" economic costs. Officials have contrasted the millions of Covid-linked deaths around the world with China's reported death toll of 5,226 since the start of the pandemic more than two years ago.
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