Xia Yong, a technician from Peking University Shenzhen Hospital, showed China Daily his hands covered in adhesive bandages.

"I've to wear medical gloves six to eight hours a day. Our hands were soaked in sweat, and the skin at the joints fell off," he said.

About 600 containers containing more than 100,000 samples are sent to the laboratory daily. For safety reasons, no extra hands were hired to help the technicians receive the containers or take them to the lab. They have to do all the manual work.

Outside the facility, all members of the mainland support team are currently under "closed management". Shuttle buses take them from their hotel to the laboratory and then back.

"Such an arrangement is to protect the team members and the people of Hong Kong," Guo explained.

When the team arrived, certain people claimed that the swabs to be used would hurt a person's brain during the test, or their genetic samples would be sent to the mainland.

Guo said they're aware that such rumors and smearing by a small minority of the Hong Kong community actually run counter to mainstream public opinion.

"As long as we stick it out and believe that what we do is conducive to the health of Hong Kong residents and the community, we'll soldier on with confidence and strength," he said.

The HKSAR government said the universal testing program will be extended until Monday, after which the team will return to the mainland to be quarantined for another 14 days before they can go home.

Although they have no time to see Hong Kong on this visit, Guo said he's confident the opportunity will come when the local outbreak is brought under control, and travel and communications with the mainland resume. "We'll certainly come and visit the place we've fought for," he said.

Guo said he expects more Hong Kong residents to take part in the mass screening program to help further check the spread of the coronavirus, and bring the city and the economy back to normal.

But what he knows for sure is that if Hong Kong were to ask for help from the mainland again, the central government and the mainland technicians will not hesitate to come again and return to the front line.

"As medical workers, our responsibility and mission is to protect lives and people's health. Moreover, the HKSAR is part of China. We, Chinese people, have this tradition of helping each other in times of difficulty," said Guo.

Sherry Tang, a local resident who works in the engineering sector, said the mainland support team is a great inspiration to her. She believes it has brought not just technicians, but also anti-epidemic experience from the successful fight against COVID-19 on the mainland.

Tang has been separated from her family on the mainland since the SAR government required all visitors from the mainland to be quarantined for 14 days from Feb 8. The measure has been extended to Oct 7.

But she thinks the separation won't last long. "This time is different. Our strong backing is here."