By 6 pm on Monday, Zhengzhou, Central China's Henan province, reported 13 locally-transmitted confirmed COVID-19 cases and 50 asymptomatic carriers during this round of outbreak. No confirmed patient is in severe condition, local authorities said at a news conference on Monday night.

Most of the infections relate to the No 6 People's Hospital, a designated hospital for COVID-19 patients. Gene sequencing results showed the first two local cases found were infected with the Delta variant, which is highly homologous to that of the patients from Myanmar being treated at the hospital, it said.

The city has quarantined 272 close contacts and 585 close contacts of the close contacts. By 6 pm on Monday, it had collected nucleic acid samples from about 9.8 million people. It is cooperating with other cities to accelerate testing the samples.

It asked residents not to leave the city if not necessary. Those who need to leave should show a negative nucleic acid test result within 48 hours before departure. It also strengthened control at the airport, railway stations and expressway exits.