The GPS tracking reflects a nationwide sense of urgency that spiked in mid-February after a 61-year-old woman known as “Patient 31” became a “super spreader” when she displayed coronavirus symptoms but ignored medical advice and refused to be tested. Instead, she continued with her daily routine, including visiting a buffet and attending her regular church services. She wound up infecting a number of other people in the city of Daegu.

Today Daegu and the surrounding province of North Gyeongsang make up the largest coronavirus cluster in South Korea by a large margin. The vast majority of the country’s cases are in the region, and nearly 70% of those have been traced back to the Shincheonji Church.

“More efficient”

“The number of self-quarantined people nationwide has reached around 30,000, and there is a limit to the human resources available to local governments to monitor these people,” said Jung Chang-hyun, the ministry official who supervised development of the app. “The app is a support service aimed at making this more efficient.”

The app is not mandatory, and because some people may have difficulty downloading or using it, the current system of monitoring through traditional telephone calls will continue. Others can simply opt out.

Equally, officials say they are taking a flexible approach to GPS tracking rather than draconian enforcement.

“People can wander out of their quarantine areas intentionally as well as by mistake,” said Jung. “But because there is a risk of secondary infection either way, we hope that the app can help block these unnecessary incidents in a more organized way.”

While he did not disclose the app’s radius of movement restriction, Jung said that the ministry is taking into account the fallibility of GPS tracking.

The app joins a repertoire of other measures launched to combat the surge of new cases in South Korea, such as drive-through coronavirus testing stations, which contribute to the country’s roughly 15,000-a-day testing capacity. Enabled by the KCDC’s policy of rigorous transparency, a slew of privately developed map services tracking confirmed carriers have also emerged, while municipal and district governments are sending regular emergency alerts to people’s phones to inform them of any new coronavirus cases.

This wealth of data has occasionally taken on a darker aspect. Online witch-hunts looking to identify and out coronavirus carriers have created an atmosphere of social fear. So have leaks of patient information, some of which has been proved to be entirely false.

“We are trying to minimize these risks by making it so that only the parties in question—the quarantine subject or the government official assigned to them—can access the app,” said Jung. “We will be thinking of ways to improve the app as we use it in the coming weeks.”

He added that the South Korean government would be prepared to share its technology with other nations that requested it. “We haven’t had other countries ask for our help by sharing it yet, but if they were to, we absolutely would,” he said.

• An earlier version of this article said the app was first being launched in North Gyeongsang province. It was, in fact, rolled out nationwide.