Shanghai reported three asymptomatic infections on Friday, the city's health commission said at a news briefing.

Two cases are inbound travelers – a 19-year-old male in Changning district and a 23-year-old female in Pudong New Area. The other case is a 71-year-old female whose regular nucleic acid test turned positive in Changning.

As of 4 pm on Friday, 141 close contacts and 131 secondary close contacts have been identified and quarantined. 

Shanghai conducted mass nucleic acid screening across the city on Thursday and Friday to detect COVID-19 cases as the weeklong National Day holiday came to an end.

On Thursday, Shanghai reported one confirmed COVID-19 case and 17 asymptomatic infections.

The confirmed case was discovered in the city's Jiading district, and tested positive for COVID-19 on Thursday after their arrival in Shanghai.

Sixteen asymptomatic infections were found during quarantine as they were close contacts of previous cases or infections, and the other was discovered in Pudong New Area when conducting nucleic acid tests among people with risk of exposure to the virus.

All people returning to Shanghai are required to take a nucleic acid test within 24 hours of arrival, while those who come from epidemic-affected areas are required to report to local communities within 12 hours of arrival. As for hotels, all guests need to present a negative test from within the previous 72 hours.

Zheng Zheng contributed to this story.