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Jeonghun Heo 1 Article
Follow-up investigation of asymptomatic COVID-19 cases at diagnosis in Busan, Korea
Miyoung Lee, Youngduck Eun, Kyounghee Park, Jeonghun Heo, Hyunjin Son
Epidemiol Health. 2020;42:e2020046.   Published online June 23, 2020
DOI: https://doi.org/10.4178/epih.e2020046
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AbstractAbstract AbstractSummary PDFSupplementary Material
Abstract
OBJECTIVES
The objective of the study was to conduct a follow-up investigation of 10 asymptomatic patients at diagnosis among the 98 confirmed coronavirus disease 2019 (COVID-19) cases reported in Busan between February 21, 2020 and March 13, 2020 to determine whether asymptomatic infection and transmission during asymptomatic period are possible.
METHODS
The study analyzed 10 asymptomatic, confirmed COVID-19 cases to determine whether asymptomatic infection is possible. We conducted in-depth interviews with patients and guardians; interviews with primary physicians; review of medical records and drug utilization review (DUR) reports; and base station-based location tracking.
RESULTS
Among the 98, confirmed COVID-19 cases reported in Busan, the study analyzed 10 (10.2%) asymptomatic patients at diagnosis. The results confirmed that two (2.0%) patients reported to be asymptomatic during the initial epidemiological investigation, but turned symptomatic before diagnosis as per the in-depth interview results. Four cases (4.0%) of early detection led to confirmed diagnosis during the incubation period and presentation of symptoms after diagnosis. In addition, the remaining four patients (4.0%), having no subjective symptoms nor specific findings on chest radiography and computed tomography, remained asymptomatic until the isolation order was lifted. With regard to whether transmission during the asymptomatic period is possible, it was found that one out of 23 household contacts of the confirmed patients was identified as an additional confirmed case after coming in close contact with an index patient during the presymptomatic period.
CONCLUSIONS
Among the 98 confirmed cases, asymptomatic infection was confirmed in four cases (4.0%). In addition, there was one additional confirmed case in which the patient was a family member who came in close contact with an index patient during the incubation period, thereby confirming that transmission during the asymptomatic period is possible. The possibility of transmission during the asymptomatic period has been confirmed; therefore, it is necessary to review the measures for expanding contact tracing that is currently being applied starting one day prior to the onset of symptoms.
Summary
Korean summary
본 연구는 부산광역시에서 무증상으로 COVID-19에 진단된 10명의 환자를 추적조사하여 무증상 감염이 가능한가, 무증상기에 전파가 가능한가에 대해 확인하였다. 조사결과 4명(4.0%)의 무증상 감염환자를 확인하였고, 환자의 무증상기에 밀접 접촉한 가족 중 1명의 추가 환자를 확인하여 무증상기 전파가 가능하다는 것을 확인하였다.
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Citations

Citations to this article as recorded by  
  • Asymptomatic Cases, the Hidden Challenge in Predicting COVID-19 Caseload Increases
    Brett Snider, Bhumi Patel, Edward McBean
    Infectious Disease Reports.2021; 13(2): 340.     CrossRef
  • Efficacy and safety of traditional Chinese medicine combined with routine western medicine for the asymptomatic novel coronavirus disease (COVID–19)
    Jiahao Wang, Xue Zhu, Yuying Sun, Xingcai Zhang, Wei Zhang
    Medicine.2020; 99(35): e21927.     CrossRef

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