Fuelled by the spread of the Delta variant the new wave has led to almost 200 infections since the virus was first detected at an airport in Nanjing. It has since spread to five provinces and Beijing.
All flights from Nanjing airport will be suspended until 11 August, according to local media.
Officials also began city-wide testing amid criticism for their “failure”.
China, which has prided itself on its zero tolerance to the virus, has reported 184 cases since July 20. More than a quarter of these have been linked to the highly contagious Delta variant.
Although infection numbers are relatively low, they are spread across the country, with the state media comparing it to the Wuhan outbreak at the start of the pandemic.
Ding Jie, deputy director at the city’s centre for disease control and prevention, said the virus matched to an infected person arriving on a flight from Russia.
“After their work was complete, due to cleaning and protective measures not meeting standards, it’s possible some staffers got infected, causing the virus to spread among cleaning staff,” Ding said.
Hundreds of thousands of people have gone into lockdown in Jiangsu province, of which Nanjing is the capital.
Zhangjiajie city, in Hunan, has ordered for all tourist sites, cinemas and theatres to close and for large gatherings to be banned in an effort to contain the virus.
The measures were announced after symptomless carriers outside the province were found to have attended a live performance at a theatre in Zhangjiajie on July 22.
Local authorities deemed all spectators in the theatre on July 22 between 6pm and 7 pm at a high risk.
More than 2,000 people attended the show and guests were seated next to each other, according to reports.
As of July 29, mainland China had a total of 92,875 confirmed Covid-19 cases, it said.
China‘s coronavirus death toll remains unchanged at 4,636.