In South Korea, streams of personal data are being used to fight the coronavirus.
But that's proving controversial for those who may be as concerned about their privacy as they are their health.
Using mobile phone location data, credit card records and CCTV, within an hour they're able to track and trace people who they think may be infected.
The fast response is well ahead of almost every other country trying to contain the disease.
The system was introduced in March, effectively removing barriers to sharing information between several authorities.
It's built on the country's 'Smart City' data platform, designed to let local authorities share urban planning information on things like population, traffic and population.
Yoon Duk-Hee is the director for Infectious Disease Management in Gyeonggi province.
"We can receive GPS information from mobile service carriers and (credit) card usage records in about 20 to 30 minutes using the system, so the time needed for epidemiological investigation, which used to take around two to three days, has been relatively shortened and it helps prevent the spread of infections."
The system got its first test with a fresh outbreak in May... traced to an area of the capital Seoul known for its nightlife.
At least 196 people were infected in just this small hotspot.
Yoon Duk-Hee: "We accessed all (credit) card usage records of the people who visited Itaewon clubs. Everyone on the visitors' list are suspected infectees, so we investigated those specific people's card usage records. We also requested GPS information, and received a full list of people who stayed in the relevant areas for over one hour during a specific time period."
Authorities' power to get hold of personal information was established by a new law five years ago.
The Infectious Disease Prevention and Control Act was introduced after the country was hit by the Middle East Respiratory Syndrome, known as MERS.
It allows health officials in South Korea to access a wide range of personal data without a court order.
Lee Jae-Myung, the governor of Gyeonggi province, says it's important such information is only used for health crises like the current pandemic.
"There might be some parts (of South Korea's contact tracing system) that western countries can't understand. But in our country, almost everyone uses smartphones and the IT industries are highly advanced, so we can access records of every smartphone which has passed by a repeater in a certain area at some point. Actually, this is a very scary reality. And such information should only be used for crises like infectious diseases."
Many countries are scrambling to develop smartphone apps that can trace the contacts of patients without revealing detailed personal information.
South Korea has chosen a different path and a more invasive approach.
Among people Reuters spoke to in a shopping mall here, there's an acceptance of the approach, but concerns about privacy, too.
"It's a violation of privacy to let everyone know where a (confirmed patient) lives, where they went, and what they spent money on. I think it'd be better if only the government knows that (information)."
"Of course protecting privacy is important, but I also think privacy should be put aside at this point, both nationally and globally. At a national or global level, lives are more important than personal privacy. Yes, personal privacy is important, but preventing an infectious disease is even more so."
With less than 300 deaths, South Korea's handling of the pandemic has left many countries reflecting on how much better they could have done themselves.
But whether they would have been prepared - or indeed able - to use the same data-capture methods, is another matter altogether.