Shanghai’s health authority on Monday reported 18 imported cases of COVID-19, the city’s highest single-day tally since mid-April.

All 18 infections were among Chinese nationals who had arrived from the United Arab Emirates last week on two separate flights. They tested positive for coronavirus during the mandatory two-week quarantine period after landing in Shanghai.

According to a reward and punishment system China’s aviation authority introduced in June, one of the two routes involved will be suspended for four weeks for having 15 infected passengers on board.

In late July, Chinese authorities announced that all people traveling from international destinations would have to show negative COVID-19 tests before boarding the plane in a bid to further contain imported cases. It is unclear whether the two Shanghai-bound flights followed this protocol.

Domestically, the northwestern Xinjiang Uyghur Autonomous Region has seen a surge in coronavirus cases over the past few weeks. As of Tuesday, Xinjiang had reported 567 symptomatic COVID-19 cases and 131 asymptomatic cases since mid-July.

Editor: David Paulk.

(Header image: An air passenger passes by a medical worker sterilizing a temporary corridor at Shanghai Pudong International Airport, Aug. 10, 2020. Yin Liqing/CNS/People Visual)