Dongguan, Guangdong province, reported a locally infected COVID-19 patient on Sunday and launched a testing effort across the city on Monday.

The patient, surnamed Jia, a 19-year-old male student at Guangzhou Xinhua University, Dongguan campus, had close contact with a patient surnamed Li, who was diagnosed in the city on Friday.

The campus was locked down, according to the city's disease control and prevention center, and authorities began testing residents and visitors across the city on Monday, excluding those in Chang'an, Humen, Dalingshan and Machong.

The provincial health commission mobilized 8,000 medical workers to assist.

The virus found in Li, the first patient detected in the resurgence since June 18, was identified by genome testing as a Delta variant but different from the one that led to the latest outbreak in Guangzhou, said Luo Dong, deputy director of Dongguan's disease control and prevention center, at a news conference on Sunday night.

The virus in Li is highly identical with that in her husband, surnamed Xiao, who was confirmed with COVID-19 on Friday, Luo said.