China added more than 13,000 new COVID-19 infections with state media reporting a case infected with a new subtype of the omicron variant.

The new iteration of the virus, isolated from a mild COVID-19 patient in a city less than 43 miles from Shanghai, evolves from the BA.1.1 branch of the omicron variant, Global Times reported, citing sequencing data from local health authorities. The report said the subtype doesn’t match other coronavirus that’s causing COVID-19 in China nor those submitted to GISAID, where scientists around the world share the coronavirus they sequenced as a way to monitor mutations.

A case in Dalian city in northern China reported on Friday also didn’t match any coronavirus found domestically, the municipal government said on its WeChat account.

Almost 12,000 of the cases reported nationwide on Saturday were labeled asymptomatic.

Vice Premier Sun Chunlan arrived in the country’s virus hot spot of Shanghai to oversee prevention efforts, as she ordered officials to curtail the outbreak “as soon as possible,” according to Xinhua. Cases in the financial hub exceeded 8,000 on Saturday including 7,788 asymptomatic infections. Shanghai will start a new round of mass testing on Monday, authorities said.

Sun, who previously went to Jilin to oversee lockdown measures in the northeast province, ordered Shanghai officials to “resolutely” conduct measures to stop the outbreak. All of the metropolis’ 25 million residents are currently under some form of quarantine.

In the city of Sanya in Hainan province, authorities suspended all transportation to stymie the spread of COVID, according to a post on an official WeChat account.