South Korea successfully controlled its second coronavirus outbreak by tracking down more than 45,000 people connected to the hotspots where the infection broke out — several nightclubs in Seoul — though privacy concerns have surfaced over how information is being collected.

A 29-year-old South Korean man who two weekends ago visited five nightclubs in Seoul tested positive for COVID-19 five days after his outing. He was the country's first local infection in four days.

Seoul Mayor Park Won-soon ordered all bars and clubs indefinitely closed following the diagnosis, and the South Korean government launched an aggressive testing, tracing, and isolation effort.

Within two weeks, South Korean officials had tracked down 46,000 people who had been in contact with known infected partygoers by using mobile phone location data, credit card records, and CCTV as part of its speedy "track and trace" coronavirus response.

More than 160 tested positive for COVID-19, according to The Washington Post.

South Korea also published information of where an infected person went on a public website.

"We accessed all of the credit card usage of the people who visited E21 clubs," Yoon Duk-Hee, the director for Infectious Disease Management in Gyeonggi province, told Reuters.

"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."

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