Every day, more than 200 officers report to Certis' headquarters and operations centre in Paya Lebar for 12-hour shifts to serve quarantine orders on people across the island.
Armed with a kit and stocked with masks, gowns, gloves, hand sanitiser and thermometers, they call at the homes of these people to serve them the orders and verify the state of their health.
They also check to confirm the homes are suitable for quarantine.
This includes ensuring that the person stays in a room with an attached bathroom, like the master bedroom of a Housing Board flat, for the duration of the quarantine.
These officers are among 700 front-line staff at the security firm, which has been engaged to also escort patients to receive care, and manages the security systems at government quarantine facilities.
With Certis being the only local security firm that serves quarantine orders, its officers have been carrying a heavier workload as the number of confirmed Covid-19 cases keeps rising.
So, how do the officers, who come face to face with people who could be infected, stay safe on the job?
Staff Sergeant (Auxiliary Police Force) Chiue Seng Yu keeps danger at bay by donning protective gear, including masks and gloves. He also takes a daily dose of vitamin C supplements provided by his employer, and disinfects himself when he returns from his assignments.
This is the third time the 39-year-old is in a battle against a virus. A 17-year veteran at Certis, he was deployed to serve quarantine orders during the severe acute respiratory syndrome (Sars) crisis in 2003 and the monkeypox outbreak last year.
"Having gone through the Sars and monkeypox assignments, I am not worried as we have been given the appropriate safety training."
He added: "Compared with Sars, we are now much more prepared, and the people we serve quarantine orders to are also well-informed and understanding."
Mr Muhammad Hasif Afiq, 29, a Certis operations manager at a government quarantine facility, said coming into contact with and monitoring both potential and confirmed Covid-19 patients is part and parcel of his job. "I work with 107 people per shift. I feel well protected as we have many safety measures in place."
The measures were intensified when a 37-year-old Singaporean officer tested positive for the virus after serving quarantine orders to two people from Wuhan, the epicentre of the virus in China.
Assistant Superintendent (Auxiliary Police Force) Nigel Quek Ping Ning said officers also regularly visit the homes of those under quarantine as well as call them three times a day, at different times, to ensure they abide by the rules.
"We definitely do face challenges but at the end of the day, we all strive towards one common goal: to fight and contain Covid-19."