Initially, the main task for the district was to conduct testing to identify those at risk of infection.

By noon on June 19, samples had been taken from more than 300,000 Fengtai residents, as medics worked day and night.

By Thursday, across Beijing, more than 10.41 million residents had received nucleic acid tests since the new cluster of locally transmitted cases emerged in the city.

This total was reported at a news conference on Friday by Zhang Qiang, a member of the city's epidemic control office who oversees nucleic acid testing.

About half of the confirmed cases were discovered through testing, according to the authorities.

Zhang said, "The tests are highly instrumental in discovering the source of infection, cutting off transmission channels and stopping the epidemic spreading."

After the first case reported on June 11 was found to be linked to the Xinfadi market, the city government quickly identified people at high risk who had been to the venue. Tests were swiftly carried out on all of them.

The city also introduced strict measures such as rapid detection and screening, centralized and home medical observation for those at high risk, as well as second tests after an observation period.

By June 16, tests had been carried out on 578,000 residents, including traders and workers at the Xinfadi market, residents in the area and people who had contact with the market.

Just 12 days later, tests had been offered to 7.5 million people, including workers at restaurants, supermarkets, shopping malls, hair and beauty salons, communities, banks and express delivery companies.

Before the new cluster occurred, the number of nucleic acid testing centers in Beijing had risen from 75 to 170. The centers can now test more than 458,000 samples a day, up from 40,000 early last month.