Citizens take PCR tests at a street sample collection booth.
Shanghai on Saturday reported a COVID-19 community case, who had been to various sites in five districts.
The city has added three high-risk areas.
The 43-year-old man, listed as an asymptomatic case, lives in Jiuliting Subdistrict in the outskirt Songjiang District.
He tested abnormal during recent regular polymerase chain reaction (PCR) screening and has been put under medical observation.
Apart from his accommodation at 106 Laiyin Road, the man had been to beauty salon in Songjiang, an art gallery and Shanghai Exhibition Center in downtown Jing'an, a villa community in Minhang, along with several other sites and residences in Putuo and Xuhui districts.
Two of his close contacts, who live in Jing'an and Baoshan districts, have tested positive. They were among the nine asymptomatic cases reported in Shanghai on Saturday morning, who tested positive during central quarantine.
A total of 255 close contacts of the new community case have been traced and placed under central quarantine.
As a result, the building he lives as well as two residential buildings he had been to were listed as high-risk areas and put under lockdown.
Other areas in Jiuliting Subdistrict in Songjiang and Dachang Town in Baoshan have now become low-risk areas.
A total of 4,412 related people have been screened, and all tested negative. Four items at the man's home have tested positive among the 46 items and environmental samples.
The National Health Commission of China has revoked the COVID medium-risk areas and secondary close contacts. If no cases are found in a high-risk area for five consecutive days, the area will be considered as low risk.
The quarantine period for close contacts of COVID-19 infections has also been cut to five days at a central quarantine facility plus three days at home, from seven and three days previously.
Editor: Xu Qing