# Risk of nosocomial coronavirus disease 2019: comparison between single- and multiple-occupancy rooms

## TL;DR

This study finds that more patients in a hospital room increases the risk of in-hospital COVID-19 infections.

## Contribution

Demonstrates a clear association between room occupancy and nosocomial COVID-19 risk using a large cohort study.

## Key findings

- Incidence of nosocomial COVID-19 increased with more patients per room, up to 38.64 cases per 10,000 patient-days in 6-bed rooms.
- Hazard ratios showed higher risk in multiple-occupancy rooms, with 6-bed rooms having 2.66 times higher risk compared to single rooms.
- Results suggest minimizing multiple-occupancy rooms to reduce respiratory virus transmission in hospitals.

## Abstract

There is an ongoing controversy regarding whether single-occupancy rooms are superior to multiple-occupancy rooms in terms of infection prevention. We investigated whether treatment in a multiple-occupancy room is associated with an increased incidence of nosocomial coronavirus disease 2019 (COVID-19) compared with treatment in a single-occupancy room.

In this retrospective cohort study, every hospitalization period of adult patients aged ≥ 18 years at a tertiary hospital in Korea from January 1, 2022, to December 31, 2022, was analyzed. If COVID-19 was diagnosed more than 5 days after hospitalization, the case was classified as nosocomial. We estimated the association between the number of patients per room and the risk of nosocomial COVID-19 using a Cox proportional hazards regression model.

In total, 25,143 hospitalizations per room type were analyzed. The incidence rate of nosocomial COVID-19 increased according to the number of patients per room; it ranged from 3.05 to 38.64 cases per 10,000 patient-days between single- and 6-bed rooms, respectively. Additionally, the hazard ratios of nosocomial COVID-19 showed an increasing trend according to the number of patients per room, ranging from 0.14 (95% confidence interval 0.001–1.03) to 2.66 (95% confidence interval 1.60–4.85) between single- and 6-bed rooms, respectively.

We demonstrated that the incidence of nosocomial COVID-19 increased according to the number of patients per room. To reduce nosocomial infections by respiratory viruses, the use of multiple-occupancy rooms should be minimized.

The online version contains supplementary material available at 10.1186/s13756-024-01454-w.