Beijing authorities have been tracking a total of 166 Covid-19 cases at a single nightclub as the city returns to normal after a two-month lockdown.
The chain of rapid spread began on Thursday last week after an infected person visited the Heaven Supermarket club in the nightlife hub of downtown Gongti.
Of the total cases, 145 were customers and the other 21 were staff members or people who came into contact with the suspect carriers.
Local government spokesman Xu Hejian said the outbreak in the capital was “fierce”.
On Monday, Beijing reported 51 new cases – 22 of which were asymptomatic, officials said.
A total of 143 cases have been reported in the Asian country, with most of them concentrated in Beijing and Shanghai.
The death toll, recorded at 5,226, remained unchanged on Monday.
Authorities have closed the premises, along with the adjacent Sanlitun shopping and dining complex until further notice.
The resurgence of nightclub cluster infections has also prompted authorities in Chaoyang District to shut down offline classes and move students to online classrooms, except for those taking placement exams at the college and high school.
School officials have been asked to postpone sports gatherings.
District officials ordered daily mass testing as hundreds of people lined up outside in long lines to get tested as part of safety protocol.
It comes more than a week after China lifted its punitive lockdown on millions of people as Covid cases spread widely.
However, officials have asked residents to follow the “zero-Covid policy” under which people must undergo mass testing, quarantines and sequestration of those who come into contact with infected people.
On Sunday afternoon, Beijing reported 33 new cases. A total of 1,997 cases have been reported in the capital since April 22.
Meanwhile, in Shanghai, officials detected three positive tests through which 502 people are likely to have been exposed among Red Rose Beauty Salon customers.
Those likely infected include people from 15 districts in Shanghai, putting several more at risk of catching the virus infection. Shanghai authorities officially ended the lockdown on June 1.