A medical worker collects a swab sample of a student for nucleic acid testing of possible COVID-19 infection at No. 1 Middle School of Lu'an City, east China's Anhui Province, May 14, 2021. Lu'an City is conducting nucleic acid tests for all residents in major urban districts of the city, starting Friday.Photo:Xinhua

A total of four local COVID-19 cases and one suspected case were reported Thursday and Friday in Lu'an city and Feixi county in East China's Anhui Province, following 20 days without any local transmission in the Chinese mainland.

Anhui reported a new confirmed case and a suspected one on Friday evening, both of which were close contacts of the previous confirmed cases.

The confirmed cases in Anhui had not been inoculated with the COVID-19 vaccine before being infected, said Dong Mingpei, deputy head of Health Commission of Anhui Province, Xinhua News Agency reported on Friday evening.

The local health authorities called on the public to get vaccinated as early as possible to protect against the coronavirus. Currently the inoculation rate in Anhui is 14.5 percent, the authorities said on Friday evening.

Local citizens in the two areas, worried about possible virus transmissions, lined up for vaccine inoculation on Friday, Anhui media reported.

At a community in Anhui's capital Hefei, where Feixi county is located, staffers told media that there are likely to be more than 2,000 people vaccinated at the community's two inoculation sites on Friday, almost three times the previous days.

The Anhui health authority announced on its website on Friday that one patient, surnamed Li, who traveled to Anhui's Lu'an in early May, was a close contact of people who returned to China from overseas. Another person, Zhang, who lives in Lu'an city, used to dine together with Li. Another close contact was confirmed as the latest patient Friday.

The official notice did not mention if the three were vaccinated.

Lu'an was upgraded to a "medium-risk area" on Friday. Anhui ordered three districts, including Lu'an, to complete nucleic acid testing within three days.

Authorities in Lu'an have so far traced and quarantined Zhang's 56 close contacts, all of whom have been tested. The test results of 11 of the 56 people, including Zhang's close family and other relatives, were negative, announced Lu'an Health Commission on Thursday, saying that the remaining results will be released to the public once they come out of the laboratory.

In Feixi county, Li's 122 close contacts have been traced and quarantined. All the results of their first round of tests were negative, according to the Feixi Health Commission.

The current inoculation rate of the COVID-19 vaccine in China is still lagging, at only about 23 percent, China's top respiratory disease specialist Zhong Nanshan said on Thursday.