Rapid transmission of coronavirus disease 2019 within a religious sect in South Korea: a mathematical modeling study

Rapid transmission of coronavirus disease 2019 (COVID-19) was observed in the Shincheonji Church of Jesus, a religious sect in South Korea. The index case was confirmed on February 18, 2020 in Daegu City, and within two weeks, 3,081 connected cases were identified. Doubling times during these initial stages (i.e., February 18 – March 2) of the outbreak were less than 2 days. A stochastic model fitted to the time series of confirmed cases suggests that the basic reproduction number ( R 0 ) of COVID-19 was 8.5 [95% credible interval (CrI): 6.3, 10.9] among the church members, whereas ( R 0 = 1.9 [95% CrI: 0.4, 4.4]) in the rest of the population of Daegu City. The model also suggests that there were already 4 [95% CrI: 2, 11] undetected cases of COVID-19 on February 7 when the index case reportedly presented symptoms. The Shincheonji Church cluster is likely to be emblematic of other outbreak-prone populations where R 0 of COVID-19 is higher. Understanding and subsequently limiting the risk of transmission in such high-risk places is key to effective control. Highlights Basic reproduction number ( R 0 ) of COVID-19 in a religious community of Shincheonji Church of Jesus was estimated to be 8.5 [95% credible interval (CrI): 6.3, 10.9], which is more than 4 times larger than the general population ( R 0 = 1.9 [95% CrI: 0.4, 4.4]) There were estimated 4 [95% CrI: 2, 11] undetected cases when the index case from the religious community reported symptom on February 7. The Shincheonji Church cluster is likely to be emblematic of other outbreak-prone populations where R 0 of COVID-19 is higher. Understanding and subsequently limiting the risk of transmission in such high-risk places is key to effective control.