Some Jurong West residents may know Dr Chua Ying Xian from the nearby Pioneer Polyclinic, where he is deputy head.
But for the last month, the 34-year-old has also been serving a completely different demographic - migrant workers at dormitories.
Shortly after the first coronavirus clusters were discovered in dormitories early last month, Dr Chua started volunteering at the 25,000-bed Sungei Tengah Lodge mega dorm.
Those early days drove him to exhaustion, he told The Straits Times.
"The first day, it was overwhelming. I thought I was mentally and physically prepared, but I wasn't," said Dr Chua, who has been in the medical service for 10 years.
He recounted how he saw as many as 120 patients in three hours during the peak of the spread in the dorm. About 80 per cent to 90 per cent of them tested positive for Covid-19.
While necessary for his safety, the full personal protective equipment he donned was uncomfortable. "It was very warm, ill-ventilated, and I remember feeling a bit nauseous after a while. The goggles would fog up and your eyes would tear and itch but you couldn't rub them," he said.
The situation is much more stable now, he added, attributing it to the Government's change in strategy and its forward assurance support, or "Fast", teams, which have helped to act as a kind of triage to manage the flow of workers reporting sick.
Dr Chua and his colleagues also found themselves playing another role: as counsellors for the workers.
"Their mental stress is real. They miss their family, they can't go out, and are anxious when they see their friends sent to hospital or reports of workers who died. It's not ideal since we're in goggles and masked up, but we do what we can to assuage their fears," he said.
On days when he does not visit the dormitories, Dr Chua continues with his rounds at the polyclinic, including its "red zone" to manage patients with Covid-19 symptoms.
There, misdiagnosis is a concern, said Dr Chua. His polyclinic handled two Covid-19 patients who had tested positive for dengue, only for later tests to confirm they did not have the mosquito-borne disease.
They were a 57-year-old woman, who was reported as the first patient here with both diseases. The other was a man, also 57. Both were later found to have only Covid-19. Dr Chua later helped to publish the cases in The Lancet medical journal.
Like other doctors, Dr Chua is worried about the risk of taking the coronavirus home.
He recalled how he would, in the initial days, sleep apart from his wife, who works at a family service centre. He also soaked his clothes in disinfectant and washed them separately.
"Now that we have more knowledge about the virus, we are more confident," he said.
Dr Chua is no stranger to volunteer work. For the last decade, he and a group of like-minded friends have travelled with charities to other countries yearly.
In recent years, he has helped underprivileged people living in the slums of Lucknow, the capital city of Uttar Pradesh, India.
The pandemic has given him a chance to help those closer to home, he said.
He now volunteers at the Jurong Apartments dorm near Joo Koon and JTC Space @ Tuas, just one and two MRT stations away from the polyclinic respectively.
Other volunteers also help with screening the workers, caring for them, and supplying medication for other medical conditions.
Seeing his patients at the dormitories get progressively better sustains him, said Dr Chua.
"It is very satisfying to treat and manage them. They smile, you can see that they look forward to getting better. It keeps us going."