Residents take tests for coronavirus at Pudong International Airport on Sunday. Photo: Courtesy of Shanghai Airport

The local COVID-19 case discovered on November 9 who worked at Pudong International Airport in Shanghai and his colleague who was confirmed the next day in Anhui Province were infected with a virus strain similar to that from North America, Shanghai authorities announced on Monday.

After genetic sequencing, the genes of the two cases were found to be highly homologous and similar to the North American virus strain, indicating that the source of infection was likely imported, Sun Xiaodong, deputy director of Shanghai CDC, said during a press conference held on Monday morning.

On November 9, Shanghai found the first new local COVID-19 case in Pudong New Area, following months without any local infections. The two patients had no contact with any confirmed or suspected COVID-19 cases nor any imported cold-chain products or related environments 14 days before they displayed syndromes, said Sun. 

However, both of them entered and cleared an aviation container that returned from North America on October 30 without wearing face masks. It was a closed container with a large amount of shock-absorbing foam and humid internal environment, noted Sun.

Shanghai on Monday reported three new confirmed local COVID-19 cases, including one new case at the Pudong airport among 17,719 samples. 

The new case reported on Monday night is a male FedEx courier among 17,719 staff members at the airport who were tested overnight on Sunday, after at least seven cases were found to be related to a cargo business at the airport in the last two weeks.

At present, the temporary sampling point at Pudong airport has been removed, Shanghai Airport Authority announced on Monday, indicating that it's only a rumor that free nucleic acid testing is being conducted at the airport.

The two local cases are both close contacts of previous confirmed patients, with 52 close contacts now under medical observation as well. 

The airport will further strengthen prevention and control in the upcoming winter months, carry out regular testing for high-risk operators in the cargo area, and arrange for them to receive COVID-19 vaccines voluntarily, the authorities said on Monday.

Shanghai also immediately declared the neighborhood at 126 Shunhe Road in Pudong New Area's Zhangjiang town — where one confirmed case was found — as a medium-risk region on Sunday. 

Meanwhile, emergency response level was downgraded to low from medium risk for Yingqian village in Pudong New Area, where the first local COVID-19 case was reported. As of Monday, the village has reported no new cases for 14 consecutive days. 

The city has declared several regions in Pudong as medium-risk areas include Xinsheng community in Zhuqiao town and Mingtian Huacheng residential area in Zhoupu town. Residents have been asked not to leave Shanghai but those who must leave will have to submit a negative test certificate for COVID-19 taken within seven days.