Due to a worsening COVID-19 situation, all the people in Chongqing's central area will undergo a free nucleic acid test on Wednesday, local authorities announced Tuesday afternoon.

The southwestern municipality has over 32 million people in 38 districts and counties, and there are about 10 million residing in the nine central districts of Yuzhong, Jiangbei, Yubei, Nan'an, Jiulongpo, Shapingba, Dadukou, Beibei and Banan.

Since the first confirmed case on Aug 3, Chongqing has reported 15 infections in various parts of the city.

"At present, Chongqing is facing uncertainty and a complicated situation in epidemic control," said Yang Lin, Chongqing government spokesperson, at a news conference on Tuesday afternoon.

He said on Wednesday all people in the central areas, including permanent and temporary residents, migrant workers and foreign passport holders, will see their health codes on their mobile phones turn from green to orange. After taking one test, the codes will return to green, which means no abnormal conditions.

Because of the extreme heat, the test will run from 6 am to noon and later from 6 pm to midnight.

For the elderly, the disabled, patients with chronic diseases and people with special needs, the community will arrange home visits for testing.