China detected 13,000 Covid-19 cases on Sunday, the most since the peak of the first pandemic wave over two years ago, as health officials said they have found 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 70 kilometres (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 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.