As of noon (0400 GMT) on Wednesday (August 4), approximately 2.5 million Wuhan residents had been sampled, according to the official Xinhua news agency.
The city has set up 2,820 sampling sites and mobilized over 18,000 medical workers and other staff members to work there, Xinhua wrote, quoting a Wuhan health official.
Wuhan, where the virus first emerged in late 2019, had reported no local coronavirus cases since mid-May last year but on Monday (August 2) authorities confirmed three cases of the Delta variant. The strain has been found in a handful of provinces and big cities including Beijing over the past two weeks.
A total of 85 new confirmed COVID-19 cases were detected in China for Wednesday (August 4), down from 96 a day earlier, data from the National Health Commission (NHC) showed. Mainland China had recorded 93,374 confirmed cases, with the cumulative death toll unchanged at 4,636.