ZHENGZHOU -- Zhengzhou, the capital of central China's Henan povince, has tightened epidemic prevention and control measures after a recent resurgence of COVID-19 infections.

Zhengzhou designated one area as high-risk and six as medium-risk for COVID-19 from Tuesday.

By 6 pm Monday, the city had reported 13 locally-transmitted confirmed COVID-19 cases and 50 asymptomatic carriers.

Zhengzhou launched citywide nucleic acid testing for COVID-19 on Sunday and over 9.8 million people had been sampled as of 6 pm Monday.