Nosocomial Outbreak of COVID-19 in a Hematologic Ward

Abstract

Background: Coronavirus disease 2019 (COVID-19) outbreaks occur in hospitals in many parts of the world. In hospital settings, the possibility of airborne transmission needs to be investigated thoroughly.

Materials and methods: There was a nosocomial outbreak of COVID-19 in a hematologic ward in a tertiary hospital, Seoul, Korea. We found 11 patients and guardians with COVID-19 through vigorous contact tracing and closed-circuit television monitoring. We found one patient who probably had acquired COVID-19 through airborne-transmission. We performed airflow investigation with simulation software, whole-genome sequencing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Results: Of the nine individuals with COVID-19 who had been in the hematologic ward, six stayed in one multi-patient room (Room 36), and other three stayed in different rooms (Room 1, 34, 35). Guardian in room 35 was close contact to cases in room 36, and patient in room 34 used the shared bathroom for teeth brushing 40 minutes after index used. Airflow simulation revealed that air was spread from the bathroom to the adjacent room 1 while patient in room 1 did not used the shared bathroom. Airflow was associated with poor ventilation in shared bathroom due to dysfunctioning air-exhaust, grill on the door of shared bathroom and the unintended negative pressure of adjacent room.

Conclusion: Transmission of SARS-CoV-2 in the hematologic ward occurred rapidly in the multi-patient room and shared bathroom settings. In addition, there was a case of possible airborne transmission due to unexpected airflow.

Keywords: Airborne transmission; COVID-19; Hematologic malignancy; Multi-patient room; SARS-CoV-2.

Figure 1. Floor plan of the entire hematologic ward (A) and floor plan of the shared shower room and Room 1 (B). The red box indicates the beds of patients with COVID-19.

COVID-19, coronavirus disease 2019.

Figure 2. Chronology of the 9 patients with COVID-19 including contact history and SARS-CoV-2 PCR results.

COVID-19, coronavirus disease 2019; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; PCR, polymerase chain reaction.

Figure 3. Phylogenetic analysis of the sequenced SARS-CoV-2 genomes.

SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

Figure 4. (A) Passive tracer distribution in male shared bathroom, hall, and Room 1 during aerosol generation for 11 minutes in bathroom, no aerosol generation for 31 minutes in bathroom, and the door of Room 1 opened. (B) Average cumulative concentration of tracer in Room 1 compared with that of the bathroom. (C) Highest concentration of tracer in Room 1 compared with the average concentration of the tracer in the bathroom.

Figure 5. Suspected transmission routes between cases.