When a man in Seoul tested positive for coronavirus in May, South Korean authorities were able to confirm his wide-ranging movements in and outside the city in minutes, including five bars and clubs he visited on a recent night out.
The fast response — well ahead of many other countries facing outbreaks — was the result of merging South Korea's already advanced methods of collecting information and tracking the virus into a new data sharing system that patches together cellphone location data and credit card records.
The Epidemic Investigation Support System (EISS), introduced in late March, effectively removed technological barriers to sharing that information between authorities, by building on the country's "Smart City" data system.