An investigation of COVID-19 outbreak among staff in nightclub A, Sukhumvit Road, Bangkok, April–May 2020

Abstract

Background: Coronavirus disease 2019 (COVID-19) investigation team conducted dead case investigation and detected linkage with a cluster in nightclub A in Bangkok. We aimed to assess magnitude of the outbreak, assess epidemiological characteristics of the outbreak, identify risk factors of transmission, and recommend control measures.
Methods: We collected the data from case investigation forms and conduct active case finding. The case was defined as any staff in nightclub A who was tested for SAR-CoV-2 by real-time reverse transcriptase polymerase chain reaction by reviewing COVID-19 joint investigation team database and interviewing staff in the nightclub. We, then, conducted retrospective cohort study among staff in the nightclub and environmental survey to identify risk factors of transmission in the nightclub.
Results: Of 67 staff, twenty-five cases (attack rate 37.3%) were identified. Thirteen closed contacts of the staff were positive in nine provinces. The male to female ratio was 1:5. The median age of the cases was 47 years old, ranged 25–65 years old. Patients’ onset dates were from March 11–31, 2020. According to multivariate analysis, we found that sharing glasses (Adjusted RR = 4.2, 95%CI 1.4–12.7) and having massage with the index (Adjusted RR = 3.9, 95% CI 1.2–12.0) were risk factors of having COVID-19.
Conclusions and discussions: Source of the outbreak might come from travelers before spreading among staff by sharing glasses. After closing the nightclub, most staff were back home and infected their families. Control measures after re-opening the pub should include avoiding sharing things among staff as well as daily screening among staff and customers.