Nearly a month after China detected its first Omicron variant of the coronavirus in a foreign returnee in Tianjin, the northern port city is facing the country’s first locally-transmitted cases involving the heavily mutated and highly transmissible virus.

A 10-year-old girl and a 29-year-old woman working at an after-school center were found to be infected with the variant, local authorities announced Saturday. Tianjin logged 31 confirmed local COVID-19 cases as of Monday evening, with many of the symptomatic cases found among primary and middle school students.

It’s unclear where the two patients were infected with the Omicron variant of the coronavirus, as authorities said they hadn’t left Tianjin in the past two weeks. They were found to be infected with the BA.1 sub lineage of Omicron, different from the country’s first Omicron case reported in the city in December.

The city, just over 100 kilometers from Beijing, where the Winter Olympics start next month, said Sunday it would start testing its 14 million residents for the virus.

“I couldn’t test on Sunday after lining up for four hours, and finally made it on Monday,” a 25-year-old woman surnamed Xia told Sixth Tone.

Amid the fresh outbreak, the Tianjin government urged residents not to leave the city, adding those who need to travel must conduct a nucleic acid test 48 hours prior to their journey and have a green health code. Authorities have also partially locked down residential communities and shut schools to prevent further spread of the virus.

Zhang Ying, deputy director of the local COVID-19 prevention and control team in Tianjin, said in a press conference Saturday that the current cases indicate “the virus has been transmitting for at least three generations,” meaning the transmission might have started earlier than previously known.

On Monday, the city of Anyang in central Henan province also reported two COVID-19 patients infected with the Omicron variant. Local authorities believed the infections were linked to the same transmission chain from Tianjin after a university student who returned from the northern city tested positive for the virus.

China logged 97 locally transmitted COVID-19 infections on Sunday, with the majority in Henan and Tianjin, according to the National Health Commission. Meanwhile, the northwestern city of Xi’an, which is in its third week of lockdown after a virus surge, reported 15 cases, and one infection was found in the southern tech hub of Shenzhen.

This story has been updated with latest COVID-19 cases from Tianjin.

Editor: Bibek Bhandari.

(Header image: People line up for COVID-19 test in Tianjin, Jan. 9, 2022. IC)