When Chinese mainland virus testing technician Guo Haopeng arrived in Hong Kong on Aug 2, he was distressed to face a protest against his mission.

Guo, as deputy head of a support team from Guangdong province for Hong Kong's Universal Community Testing Program, is co-leading a 400-plus-strong team to help the city boost its virus testing capacity under the program, which started on Sept 1 and has now been extended by three days to Sept 14.

The special administrative region is still battling the third wave of COVID-19 infections that struck in early July. More than 2,060 infections, accounting for 42.1 percent of the city's total confirmed cases, were recorded in that month alone.

Before Guo's team arrived, Hong Kong could process up to 10,000 samples daily itself. But it fell short of the capacity needed to contain the third wave, described as the most serious since the first local confirmed case was reported earlier this year.

Chief Executive Carrie Lam Cheng Yuet-ngor had written to the central government in late July seeking assistance, including boosting the daily virus testing capacity and setting up community treatment facilities.

Guo was assigned the task in late July just after having returned to Guangzhou from Beijing, where he had led a team of about 20 people to help Beijing Tian Tan Hospital of Capital Medical University bring the city's cluster of COVID-19 infections at the Xinfadi wholesale market under control. After the arrival of his team, the hospital's daily testing capacity increased from 4,000 to 13,000 in one month.

Guo and a preliminary group of nine other members came to Hong Kong on Aug 2 as the vanguard of the supporting team. A group of local residents had gathered outside their hotel, not to welcome them, but to stage a protest.

"The very first words I heard when I arrived here were: 'What do you think you could bring to Hong Kong?'" recalled Guo. The question came from a woman in a shrill tone.

"Those words hurt every member of our team to some degree," said Guo.

Hong Kong's citywide virus testing program, being conducted on a voluntary basis, has detected 19 infections of the coronavirus out of a total of around 1.27 million specimens collected under the program as of 8 pm on Wednesday.

"I think this is the answer to the question we were asked on the first day we arrived here," said Guo.

"We've identified a few positive COVID-19 cases, which is very important in giving the community a better idea of how to fight the pandemic in order to cut off possible chains of transmission."

Currently, 427 mainland technicians, handpicked from different hospitals and medical institutions in Guangdong and Fujian provinces, as well as the Guangxi Zhuang autonomous region, are working with 200 Hong Kong medical personnel at the Huo-Yan Laboratory set up at the Sun Yat Sen Memorial Park Sports Centre in Sai Ying Pun. The facility is capable of handling more than 200,000 samples a day.