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Coronavirus Disease Exposure and Spread from Nightclubs, South Korea

Our take —

Contact tracing conducted by the Seoul Metropolitan Government and the Seoul Metropolitan Police Force due to an outbreak of COVID-19 among those who attended nightclubs in the Itaewon area from April 30 to May 6, 2020 resulted in 246 cases out of 41,612 attendees/contacts tested. Though the testing positivity rate was low, the number of cases was substantial in the context of the national epidemic, and highlights the potential for mass gathering to result in cluster outbreaks even in locations where the epidemic is largely under control. This highlights the challenges of efficiency and scale of contact tracing and required resources to effectively implement contact tracing to achieve epidemic control as in South Korea.

Study design

Cross-Sectional

Study population and setting

South Korea reopened nightclubs April 30 before the Golden Week holiday (April 30 to May 5, 2020). On May 6, cases were reported of COVID-19 from people who visited nightclubs in the Itaewon area (located in downtown Seoul) and infected contacts located throughout the country. On May 9, the Seoul Metropolitan Government and the Seoul Metropolitan Police conducted contact tracing for everyone who visited five major nightclubs in Itaewon between April 30 and May 6, 2020. Data in this analysis includes all testing performed by May 25, 2020. No information was provided related to mask mandates or use in the nightclub.

Summary of Main Findings

Investigators found that there were a reported 246 cases associated with the nightclub gatherings including 96 primary cases and 150 secondary cases. These cases come from 41,612 test (35,827 from nightclub attendees and 5,785 attendee contacts). They used information technology including credit card transactions, mobile device data, and public transportation pass records to find people who needed tests. Of the tests conducted, the prevalence of COVID-19 among night club attendees was 0.19% and 0.88% among contacts. Overall, the 246 cases emerging from nightclub attendance during that one-week attributed to 2.3% of South Korea’s cumulative cases at that point.

Study Strengths

The majority of cases were linked to gay nightclubs, and there was stigma surrounding people of the LGBTQ community as people falsely blamed them for starting the outbreak. Study investigators connected with leaders in the LGBTQ community concerning best practices on reducing the stigma around COVID-19 testing given the current climate. Investigators in turn provided anonymous testing options. This allowed them to obtain 1,627 additional tests that they would not have had otherwise.

Limitations

A potential limitation is that although the methods of the study provide a depiction of the labor that went into finding people to test, the effort yield very few cases given the number of tests (positivity rate: 0.6%). No information related to mask mandates or use was provided; the risk of nightclub transmission should be interpreted carefully, in the context of the local epidemic at the time (low background circulating virus) and unknown mask use.

Value added

This study shows an impressive effort in tracking down potential cases and contacts in order to control an acute outbreak as they were able to map out cases to the 6th wave of transmission.

This review was posted on: 31 July 2020