The eastern Chinese city of Nanjing announced a second round of city-wide coronavirus nucleic acid testing starting at 11 a.m. on Sunday.

A total of 57 positive COVID-19 cases were detected in the first round of testing as of Saturday, local authorities said.

Two confirmed and two asymptomatic COVID-19 cases were registered in Nanjing on Saturday. A total of 37 confirmed and 20 asymptomatic patients are under isolated medical treatment and observation.