Jiegao, a border community in Ruili, Yunnan province, became the country's only medium-risk area for COVID-19 on Tuesday after reporting three new confirmed locally transmitted cases and two locally transmitted asymptomatic carriers on Monday, local authorities said.

The five cases, all from neighboring Myanmar, were sent to a designated hospital for treatment. The city reported three confirmed locally transmitted COVID-19 cases on Sunday. All those infected were discovered during nucleic acid testing in Jiegao, and none is in serious condition, Shang Labian, mayor of Ruili, told a news conference on Tuesday.

Ruili is seeing its third epidemic outbreak in a year, following outbreaks in September and March. Yunnan Governor Wang Yubo and a national guidance group have arrived in the city to offer help.

By 8 am on Tuesday, the city had collected 238,794 samples in the 24 hours since a new round of citywide nucleic acid testing kicked off. A total of 761 close contacts of infected people as well as their close contacts have been quarantined, Shang said.

Eight locations where people can enter and leave the city are under strict management. Jiegao residents are quarantined at home and people in other parts of Ruili can only leave the city after getting approval from the local authorities and with good cause.

The city has opened five 24-hour telephone hotlines to answer inquiries from the public, especially visitors stranded in Ruili, and to provide psychological counseling.

Supplies of daily necessities and medical materials such as face masks are sufficient and prices remain stable, Shang said. By 8 am on Tuesday, the city had 14,050 metric tons of grain reserves and 250 tons of rice. There are three designated supermarkets in Jiegao to guarantee the supply of goods. Community workers will deliver daily necessities to Jiegao residents.

Shang said patients are getting targeted treatment that combines traditional Chinese medicine and Western medicine, prevents severe cases or deaths, and avoids medical workers getting infected. Results of mass nucleic acid testing will be released as soon as possible. The city will also strengthen a crackdown on cross-border crimes like smuggling and stowaways.

"We will strengthen efforts to prevent the spread of the virus and control the epidemic to the maximum degree as soon as possible," he said.

Yu Chuanhua, a professor at the School of Health Sciences at Wuhan University, told China Central Television on Monday night that Ruili shares a border of about 170 kilometers with Myanmar, and exchanges between people on both sides are frequent, posing challenges in epidemic control.

He added that the recent COVID-19 outbreak in Ruili is unlikely to spread to a broader area due to the city's high vaccination rate and previous experience fighting the novel coronavirus.