Shanghai reported an imported asymptomatic COVID-19 case yesterday, the city's Health Commission said today.

The patient is a Chinese studying in the United States who arrived at Pudong International Airport on December 21. During the two-week quarantine, the patient tested negative for COVID-19 four times.

During the following seven-day self-health monitoring, the patient tested positive on the last day without showing symptoms.

Health authorities tracked down 37 close contacts who have been placed under medical observation.

The patient visited Wanchun Street in Jing'an District and a Cantonese-style restaurant on the B1 floor of the Jiuguang shopping center near Jing'an Temple.

A total of 4,852 people have been screened and have all tested negative. Another 568 environmental samples have been collected, among which 17 from the patient's residence were positive.

Shanghai reported 20 imported COVID-19 cases, one imported asymptomatic case, and no new locally transmitted infections yesterday.

Authorities reiterated that during the self-health monitoring period, people are not allowed to take public transport, gather for meals or dine in restaurants, participate in such activities as watching movies, exhibitions or meetings. Visits to indoor places such as cinemas, supermarkets, offices or KTV are also not permitted.