From the movements and contacts of the first people with confirmed cases of covid-19 in South Korea, we get a real-life picture of how a disease spread through a vulnerable population.
skorea cases network
Jan. 20 1 known case
The country’s first known case was a 35-year-old Chinese woman who arrived at Incheon Airport from Wuhan. She tested positive for the novel coronavirus on Jan 20.
Jan. 27 4 known cases
Within a week, there were three more known cases, all travelers from Wuhan and all in their 50s. Two were detected and isolated at airports, so it is very unlikely they passed the disease to anyone else.
Jan. 30 7 known cases
Three additional people were confirmed to have the virus. Two were from Wuhan, and one was a man who had eaten a meal at a restaurant with Patient 3. He would become Patient 6, the first known case of local transmission () in South Korea.
Jan. 31 11 known cases
The next day, Patient 6’s wife and son were confirmed positive, as well. Eleven days after the first case was diagnosed, there were just 10 other known cases. Local transmission had occurred only among family members or within close social circles.
Feb. 2 15 known cases
The first case of transmission between strangers was documented when an airline passenger tested positive after sitting near an infected person on a flight.
Feb. 16 30 known cases
Nearly all local transmission was still among families and friends.
Feb. 18 39 known cases
Patient 31, a 61-year-old woman, became the first congregant at Shincheonji Church of Jesus in Daegu to test positive. It was unclear where she contracted the virus.
Feb. 20 104 known cases
Within two days after Patient 31 tested positive, 15 more people connected to the Shincheonji church were confirmed to have the virus, as well. A month later, thousands of people with connections to the church would test positive for the virus.
While the virus ravaged the church, more than 100 new cases had been confirmed in surrounding Daegu, as well. The disease appeared in hospitals, housing for the elderly and other churches. Most of these additional clusters were near the Shincheonji church.
March 25 9,137 known cases
A little over one month later, the cluster at the Shincheonji church accounted for 5,080 confirmed cases of covid-19, more than half of South Korea’s total.

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After the country’s biggest cluster of infections emerged among the Daegu congregation, the South Korean government ordered testing on more than 200,000 members of the Shincheonji church across the country. Thousands tested positive for the virus, including some who showed no symptoms.

Officials mandated rigorous inspections at gathering places deemed to be high risk, such as hospitals, gyms, karaoke bars, nursing homes, call centers and computer cafes.

The government reacted quickly with other policies, as well, hoping to isolate the virus from the uninfected population. Officials closed schools and public places, shut down sporting events and banned large gatherings.

The tactics appear to have worked. The rate of new known infections in South Korea has markedly slowed from a peak of 909 new cases on Feb. 29 to 100 or fewer new cases on most days since mid-March.

But the country is remaining vigilant and has continued thorough testing to track the spread of the virus.

[Mapping the spread of the coronavirus in the U.S. and worldwide]

Youjin Shin

Youjin Shin works as graphics reporter at The Washington Post. Before joining The Post, she worked as multimedia editor at the Wall Street Journal and a research fellow at the MIT SENSEable city lab.

Bonnie Berkowitz

Bonnie Berkowitz is a reporter in the Graphics department at The Washington Post who often focuses on Health & Science topics.

Min Joo Kim

Min Joo Kim is an assistant reporter for The Washington Post in Seoul. She covers news from South and North Korea.

About this story

Korea Centers for Disease Control and Prevention (KCDC); additional information compiled from major Korean newspapers