They make a commitment to serve the public and their commitment carries on, even into retirement, as the city struggles against the scourge of the coronavirus epidemic.

Men and women, current and retired officers of the city's different disciplined branches, including the Fire Services Department and the Customs and Excise Department, have stepped into the front lines, checking on the well-being of those under mandatory quarantine who are potential carriers of the disease.

Latest figures show that the novel coronavirus has infected 74 people in Hong Kong. Two patients have died.

Anson Tsui Hung-cho put on goggles and a mask on Friday morning and joined three other members of the Hong Kong Disciplined Services Volunteer Corps to make their first rounds, checking on people's welfare and ensuring that the quarantine is respected. Tsui admits his efforts may be of little actual help, but the call was made and he answered it.

The group set out for the heavily populated community of Sham Shui Po. Their mission is to check on travelers who had come across the boundary from the mainland, to face a mandatory 14-day quarantine, which conventional wisdom holds to be the incubation period for the virus. Each member of the group carried a small bag containing disinfectants and disposable gloves.

Tsui admitted to feeling a little nervous. He told China Daily he had prepared a change of clothing when the day's mission was completed. "After all, you can't see the virus and those  you are in contact with are in high-risk areas," he said.

The call for volunteers was sounded in an online chat room, operated by corps management.  From Feb 17 to Sunday, volunteers visited around 300 households, ensuring that the quarantine was not broken.

Tsui reckoned his efforts would ease the burden on front-line officers. Since Feb 8, when the edict came into effect, 13,694 people have been placed under mandatory home quarantine. The burden of maintaining the quarantine fell on active members of the police force. Added to their responsibilities was a requirement for making checks, spot checks and telephone checks in addition to their routine duties.

"As long as I am prepared and stay alert, there will be no problem," he said.

The small group checked in on an elderly couple who are confined to their home in a public estate. The elderly have difficulty with smart phones, but they are important as the government relies on the phones to keep track of locations. Since the couple had no cellphones, Tsui asked them to come to the door and he set tracking bands on their ankles. With GPS, the bands can locate the couple without smart phones.

Mak Kam-fai, retired firefighter and chairman of the corps, told China Daily that the volunteers focus on seniors who don't use smart phones. "When they cross the borders, port officers take down their home address, then we do the follow-up checks to ensure they stay home," Mak said. Volunteers often help seniors buy daily necessities.

Volunteers also take key roles in call centers. They help police regulars make phone calls to those under quarantine. Mak says that every quarantined person is required to be called every two hours. The volunteers help with the workload of over 100,000 calls a day.

Mak established the corps right after Typhoon Mangkhut battered the city in September 2018, calling together disciplined officers, retired or not, to help the city recover. In late January this year, 10 minutes after he sent out the first call for quarantine and infection volunteers, over 200 declared they were in.

"Disciplined services officers are committed to the society. When they are on duty, they are at the forefront against the virus. When they are off duty, they also come out and contribute. I respect them," Mak said.

Mak recalls one incident in particular. On Feb 12, when he received an urgent request from the government — to deliver furniture from Fai Ming Estate in Fanling to Chun Yeung Estate in Fo Tan.

The two public housing estates were requisitioned by the government to serve as quarantine centers. The Fai Ming Estate, however, was trashed by masked protesters, leaving the Chun Yeung Estate the only option remaining for the city.

The facility was required to be ready the following day when over 300 Hong Kong passengers were to fly home from the virus-stricken Diamond Princess cruise ship, anchored off Japan.

Mak got the request at 3 pm. The call was posted in the chat room. Mak felt uneasy about getting as many volunteers as needed on such short notice. But there was no alternatives. Lifts at the vandalized Fai Ming Estate were so badly damaged that they were no longer usable.

Mak had prepared to work overnight. When he arrived at the Cheung Yeug Estate, he was gratified to see that 50 volunteers had arrived ahead of him. By 8 pm, the work was finished. More than 100 volunteers had taken part.

The corps' achievements are well recognized. The China Pacific Insurance Co has provided the corps HK$12 million (US$1.54 billion) in insurance. Mak said that was an "encouraging" gift to all members.

The coronavirus is invisible to the naked eye, but the zeal and commitment to society from those of the Disciplined Services are in plain sight, for all to see.