Contact tracers with the Ministry of Health (MOH) often face numerous stumbling blocks in the race against time to map out a patient's past activities, as they struggle to get information out of forgetful and sometimes severely ill patients in the process.
But this process has been sped up with the introduction of national check-in system SafeEntry in April.
Contact tracers now use SafeEntry logs of locations that patients have been to as a reference to jog their memory during interviews.
This has been the experience of MOH senior manager Cheryl Tang, 35, who heads a team of 80 in contact tracing at the ministry.
The authorities have called for people to use digital tools, like SafeEntry and TraceTogether, to aid contact tracing which they said can speed up work for contact tracers like Ms Tang.
Ms Tang said SafeEntry has added an element of precision to their work, as the check-in and check-out data gives contact tracers a better idea of how long a patient has spent at different locations.
This has allowed the Health Ministry to accurately collate a list of places visited by infectious patients.
"(SafeEntry) also enhanced the accuracy and completeness of the activity maps," said Ms Tang.
Contact tracers list down all the activities and interactions a Covid-19 patient has had in the two weeks prior to the onset of symptoms and until the patient is isolated to ring-fence potential cases and find the origins of the infection.
The manpower-intensive process used to take several days, as contact tracers from different agencies have to call patients and their contacts, make house visits and even scour reams of closed-circuit television footage to identify and locate close contacts.
Ms Tang recalled an instance where she had to track down an acquaintance of a Covid-19 patient, who had held a gathering in her home.
While the patient had provided contact tracers the names and contacts of her guests, she forgot to mention an acquaintance whom a friend had brought to the gathering.
It took the contact tracers an additional day to contact and serve a quarantine order on the acquaintance, Ms Tang said.
If everyone at the party had used TraceTogether, the contact tracers would have been able to retrieve the acquaintance's number almost immediately, she added.
However, she acknowledged that the extent of TraceTogether's usefulness has not been seen yet due to enforced social distancing and the low community spread.
"For the app to really demonstrate its effectiveness to the full potential, I think we really need more people to use the app," she said.
To date, around 2.1 million people have downloaded the app.
While SafeEntry has helped to cut the contact tracing process to one to three hours, this may change during the current reopening, as people start to gather in groups and in more places, Ms Tang said.
It is critical for the community to diligently use SafeEntry by checking in and out of locations, and to download and actively use the TraceTogether app, she added.
"We want to be able to quickly ring-fence cases, so as to prevent a resurgence of a lot of cases in the community."
MOH senior manager Cheryl Tang said SafeEntry has added an element of precision to their work, as the check-in and check-out data gives contact tracers a better idea of how long a patient has spent at different locations.