A customer buys pickles at a local wet market in Shanghai.

Shanghai reported a COVID-19 community case on Thursday, who had been to several fresh food markets in downtown.

The city has thus enhanced COVID-19 prevention and control measures at wet markets, requiring all of their employees to get the full vaccine dose and the booster shot, if eligible.

The asymptomatic case, a 31-year-old female, lives in Daqiao Subdistrict of Yangpu District. She tested abnormal during recent regular polymerase chain reaction (PCR) screening and has been put under medical observation.

Apart from her accommodation at 1315 Changyang Road, she had been to three fresh food markets on Changyang and Meizhou roads in Yangpu, according to the Shanghai Health Commission.

As a result, her accommodation and nearby street shops were designated as medium-risk areas and put under lockdown.

A total of 524 close contacts of the new case have been traced and placed under central quarantine. Among them, 421 have tested negative.

A local traditional wet market is relatively empty, with few customers.

A total of 30,697 related people have been screened, and all tested negative.

Visitors to local wet markets must have a 72-hour negative PCR test report and the green health code, as well as receive temperature checks at the entrance.

All wet market employees, including managers, business operators, porters and service staff, must receive a daily PCR test and take the two courses of the COVID-19 vaccine.

And eligible people must also receive the third booster shot, according to the city's official WeChat account Shanghaifabu.

The city's commerce authority has already launched a pandemic-linked overhaul of local wet markets, mainly on venue code scanning among visitors, employees' self-protection and daily PCR tests, as well as environment disinfection and emergency response.

Meanwhile, 20 sports venues, mainly gyms and indoor basketball courts, in Yangpu were punished on Wednesday for violating COVID-19 prevention and control rules.

A regular inspection targeting sports venues is being held across the district to curb the spread of the coronavirus, according to Yangpu's sports bureau.