J Korean Med Sci.  2021 Jun;36(24):e179. 10.3346/jkms.2021.36.e179.

Source Analysis and Effective Control of a COVID-19 Outbreak in a University Teaching Hospital during a Period of Increasing Community Prevalence of COVID-19

• Lee U
• Kim SE
• Lee SY
• Wi HN
• Choi O
• Park JW
• Kim D
• Kim YJ
• Shin HY
• Kim M
• Kim EJ
• Kang SJ
• Jung SI
• Park KH

• KMID: 2516768
• DOI: http://doi.org/10.3346/jkms.2021.36.e179

Abstract

Background
South Korea has been experiencing a third wave of coronavirus disease 2019 (COVID-19) since mid-November 2020. Our hospital in Gwangju metropolitan city experienced a healthcare-associated COVID-19 outbreak early in the third wave. The first confirmed COVID-19 patient was a symptomatic neurosurgery resident with high mobility throughout the hospital. We analyzed the transmission routes of nosocomial COVID-19 and discussed infection control strategies.
Methods
We retrospectively analyzed the severe acute respiratory syndrome coronavirus 2 reverse transcription-polymerase chain reaction (RT-PCR) testing results according to time point and evaluated transmission routes.
Results
Since COVID-19 was first confirmed in a healthcare worker (HCW) on 11/13/2020, we performed RT-PCR tests for all patients and caregivers and four complete enumeration surveys for all HCWs. We detected three clusters of nosocomial spread and several sporadic cases. The first cluster originated from the community outbreak spot, where an asymptomatic HCW visited, which led to a total of 22 cases. The second cluster, which included patient-to-patient transmission, originated from a COVID-19 positive caregiver before diagnosis and the third cluster involved a radiologist and a banker. We took measures to isolate Building 1 of the hospital for 17 days and controlled the outbreak during a period of increasing community COVID-19 prevalence. Universal screening of all inpatients upon admission and resident caregivers was made mandatory and hospital-related employees are now screened monthly.
Conclusion
Infection control strategies to prevent the nosocomial transmission of emerging infectious diseases must correspond with community disease prevalence. Our data reinforce the importance of multi-time point surveillance of asymptomatic HCWs and routine surveillance of patients and caregivers during an epidemic.

Keyword

SARS-CoV-2; Nosocomial Transmission; Outbreak; Infection Control

Figure

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  Fig. 1 Estimated transmission routes of COVID-19 cases who were diagnosed within CNUH or were epidemiologically associated with CNUH. (A) The in-hospital transmission during the neurosurgery (NS) department outbreak. Discharged patients and a caregiver from NS ward were transferred to other hospitals in Mokpo city and Seongnam city. (B) Intra-hospital transmission involving 10 COVID-19 patients. (C) Related COVID-19 cases in a private company (KJ bank). (D) Sporadic cases. The numbering of the COVID-19 case symbols represents the order in which the cases were diagnosed in the laboratory of CNUH during the complete enumeration survey. Blue coloring indicates COVID-19 cases that were diagnosed during the self-isolation period and yellow coloring indicates family members within a transmission group. Symbols with a grid pattern represent COVID-19 cases that caused community transmission after discharge.C.S.D = central supply department, COVID-19 = coronavirus disease 2019, CNUH = Chonnam National University Hospital.

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  Fig. 2 Floor plan of Chonnam National University Hospital and the sites of coronavirus disease 2019 occurrences. The areas of each cluster of intra-hospital transmission are colored similarly. Green areas represent the predicted sites of sporadic cases originating from outside the hospital.ICU = intensive care unit, EICU = emergency intensive care unit, CCU = coronary care unit, OPD = outpatient department.

• 

  Fig. 3 Timeline of the COVID-19 outbreak in CNUH. The red boxes indicate each COVID-19 case diagnosed in the CNUH laboratory. Layered red boxes represent the number of COVID-19 patients diagnosed per day. Numbers in the red boxes represent the temporal order of diagnoses in CNUH and correspond to the numbered cases in Fig. 1. Green graph (top) represents the number of SARS-CoV-2 PCR tests performed per day. Red and black graphs (bottom) represent the number of COVID-19 cases in South Korea and the surrounding community.CET = complete enumeration test, HCW = healthcare worker, COVID-19 = coronavirus disease 2019, CNUH = Chonnam National University Hospital, SARS-VoV-2 = severe acute respiratory syndrome coronavirus 2, PCR = polymerase chain reaction.

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