For the past month, South Korean residents have been receiving flurries of emergency text messages from authorities, alerting them to the movements of local people with COVID-19. Epidemiologists say that detailed information about infected people’s movements is crucial for tracking and controlling the epidemic, but some question whether it’s useful to make those data public. Some say it could even be harmful.

The first cases in the country were reported in late January, and then surged a few weeks later. As case numbers grew, authorities launched a massive contact-tracing and testing regime to identify and then isolate infected people, even setting up drive-through testing centres. So far, the country has tested more people per capita than any country in the world — a total of nearly 300,000 people. As of 17 March, the country had reported 8,413 cases.

When a person tests positive, their city or district might send out an alert to people living nearby about their movements before being diagnosed. A typical alert can contain the infected person’s age and gender, and a detailed log of their movements down to the minute — in some cases traced using closed-circuit television and credit-card transactions, with the time and names of businesses they visited. In some districts, public information includes which rooms of a building the person was in, when they visited a toilet and whether or not they wore a mask. Even overnight stays at ‘love motels’ have been noted.

Other countries, including Singapore , have released data such as the age or gender of people with COVID-19, but nothing as detailed as in South Korea.

Public trust

The South Korean government says the public is more likely to trust it if it releases transparent and accurate information about the virus, including travel histories of confirmed patients. Laws passed since the country's last major disease outbreak, of Middle East respiratory syndrome (MERS) in 2015, now specifically allow authorities to publish this information.

Numerous websites and smartphone apps have also sprung up to collect and map the data, such as coronamap.site . Checking the maps has become part of daily life for many South Koreans.

Experts and the World Health Organization say that South Korea’s extensive tracing, testing and isolation measures — along with campaigns encouraging people to avoid large gatherings — have helped to reduce the virus’s spread. Over the past two weeks, the number of new cases being reported each day in South Korea has dropped dramatically, from a peak of 909 cases announced on 29 February to 74 on 16 March.

But the specificity of the publicly available data has raised privacy concerns. The data trails released about some of the infected people have been so detailed that they could be identifiable, say some researchers and human-rights activists.

It might be useful for epidemiologists to “privately and securely have this information on hand, especially for contact tracing”, says Maimuna Majumder, a computational epidemiologist at Boston Children’s Hospital in Massachusetts. But she says she’s not sure that publicizing such information is worth the risk of exposing people to the social stigma that might come if their community knows they are infected. The potential for stigma could even dissuade some infected people from coming forward to get tested, says Majumder.

Human-rights concerns

On 9 March, Choi Young-ae, chair of the National Human Rights Commission of Korea, also expressed concern that the “excessive disclosure of private information” could cause people with symptoms to avoid testing.

In response, South Korea’s Centers for Disease Control and Prevention said on 14 March that such detailed location information should be released only when epidemiological investigations could not otherwise identify all the people with whom an infected person had been in contact before their diagnosis.

The idea is that a person with mild symptoms can check the travel logs to see whether they might have come in contact with an infected person, which could help medical officials decide who should be screened, says Sung-il Cho, an epidemiologist at Seoul National University. He thinks authorities are justified in making location information public for this purpose.

But he says an unintended consequence has been that people are avoiding places that an infected person has visited, even though the places have been closed and cleaned since then.

Personal hygiene and social distancing are more important than looking up websites to avoid places that infected people have visited, says Oh Myoung-don, an infectious-disease physician at Seoul National University.

Legacy of infection

South Korea’s data transparency during this outbreak has its origins in how the government handled the 2015 outbreak of MERS, which reportedly infected 186 people in South Korea and killed 36. The government at the time initially refused to identify the hospitals in which infected people were being treated, but a software programmer made a map of cases based on crowdsourced reports and anonymous tips from hospital staff. Eventually, the government relented and named the affected hospitals.

The public broadly supports the government publishing individuals’ movement, says Youngkee Ju, a researcher in health journalism at Hallym University in Chuncheon. In 1,000-person surveys that he co-authored, published in February and earlier this month, most respondents supported the government sharing travel details of people with COVID-19. Furthermore, most “preferred the public good to individual rights”, says Ju. He and his colleagues intend to perform a follow-up survey to find out exactly how much personal information the public supports disclosing.