Epidemiologic Linkage of COVID-19Outbreaks at Two University-affiliated Hospitals in the Seoul Metropolitan Area in March 2020

Background@#Coronavirus disease 2019 (COVID-19) outbreaks emerged at two universityaffiliated hospitals in Seoul (hospital A) and Uijeongbu City (hospital S) in the metropolitan Seoul area in March 2020. The aim of this study was to investigate epidemiological links between the outbreaks using whole genome sequencing (WGS) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). @*Methods@#Fifteen patients were enrolled in the study, including four non-outbreak (A1–A4) and three outbreak cases (A5–A7) in hospital A and eight cases (S1–S8) in hospital S. Patients' hospital stays, COVID-19 symptoms, and transfer history were reviewed. RNA samples were submitted for WGS and genome-wide single nucleotide variants and phylogenetic relationships were analyzed. @*Results@#The index patient (A5) in hospital A was transferred from hospital S on 26 March.Patients A6 and A7 were the family caregiver and sister, respectively, of the patient who shared a room with A5 for 4 days. Prior to transfer, A5 was at the next bed to S8 in the emergency room on 25 March. Patient S6, a professional caregiver, took care of the patient in the room next to S8's room for 5 days until 22 March and then S5 for another 3 days.WGS revealed that SARS-CoV-2 in A2, A3, and A4 belong to clades V/B.2, S/A, and G/B.1, respectively, whereas that of A5–A7 and S1-S5 are of the V/B.2.1 clade and closely clustered. In particular, SARS-CoV-2 in patients A5 and S5 showed perfect identity. @*Conclusion@#WGS is a useful tool to understand epidemiology of SARS-CoV-2. It is the first study to elucidate the role of patient transfer and caregivers as links of nosocomial outbreaks of COVID-19 in multiple hospitals.

Job Stressors in Subway Workers and Firemen / 대한산업의학회지

OBJECTIVES: To determine the job stress factors of subway workers and firemen and to develope appropriate stress management systems for the works places. METHODS: The study subjects comprised 1,826 male subway workers and 538 male firemen residing in Daegu metropolitan city. The Korean Occupational Stress Scale (KOSS) questionnaire was used. RESULTS: The median values of the study subjects were lower than the reference values. The categories of physical environment and insufficient job control were more stressful to firemen while the organization system category was stressful to both subway workers and firemen (p<0.05). There was no statistical difference in the stress factor of the interpersonal conflict category. Among the firemen, the physical environment category was more stressful to field work department workers than to desk workers (p<0.05). CONCLUSION: The study results suggested that interpersonal conflict and organization system categories are stressful to male subway workers and firemen. Especially, effective control of firemen's physical environment stress factor is needed.

A Case of Argyria from Silver in Cellular Phone Case Manufacture / 대한산업의학회지

BACKGROUND: Skin contact with, and the breathing in of air containing silver compounds can occur in the workplace. Occupational exposure to silver and its compounds is mainly via airborne dust, metal fumes, and mists of solutions containing silver compounds. Argyria results from increased serum silver levels and the deposition of silver-containing particles in the dermis and mucous membranes. The author reports a patient with generalized argyria, who worked on the manufacture of cellular phone cases. CASE REPORT: The patient was a 30 year-old male, with extensive blue-gray discoloration of the whole body, especially sun-exposed area, of 3 years duration. He had been exposed to silver in the processing of EMI for the past 4 years and gaskets for 1 year. EMI is the process by which the internal electromagnetic wave in cellular phone cases are shielded, and gaskets play an important role in shielding the electric clashes between electronic circuits, as well as increasing the durability of cellular phone cases to impact. EMI had been processed manually but this was changed to automatic spraying by robots in 2003. On physical examination, the patient had diffuse blue-gray discoloration of the skin, which was most prominent in the sun-exposed areas of his face, neck and V of the chest. Histopathological examination of a punch biopsy specimen from the posterior neck revealed fine, minute, round, and brown-black granules deposited in the basement membrane zone surrounding the eccrine glands. The laboratory findings were positive for hepatitis B antigen, with a serum silver concentration of 150.3 ppb. From this evidence, he was diagnosed with argyria due to silver exposure. DISCUSSION: The author reports a case of occupational systemic argyria due to inhalation exposure of silver compounds.