DETECTION of SARS-CoV-2 RNA on the floors of healthcare worker-only areas in hospitals is strongly associated with impending COVID-19 outbreaks in hospital wards, suggesting that floor sampling could be an important tool for outbreak prediction. This study explored whether the viral presence on floors in hospitals could serve as a predictor for COVID-19 outbreaks, following earlier findings in long-term care facilities.
To investigate this, weekly floor swabs were collected prospectively from staff locker rooms and other healthcare worker-only areas in two hospitals in Ontario, Canada, over a 39-week period. The swabs were tested for SARS-CoV-2 RNA using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR), and results were reported as the percentage of positive swabs and viral copy numbers. A statistical model was then used to assess the relationship between viral detection and COVID-19 outbreaks in these hospitals. Out of 760 swabs, 71% tested positive for SARS-CoV-2 RNA. At Hospital A, 90% of floor swabs were positive (95% CI: 85%–93%), and at Hospital B, 60% were positive (95% CI: 55%–64%). During the study, there were four outbreaks at Hospital A and seven at Hospital B, primarily involving patients. Statistical analysis revealed that for every 10-fold increase in viral copies, there was a 22-fold increase in the odds of a COVID-19 outbreak (OR = 22.0, 95% CI: 7.3–91.8). The predictive model demonstrated strong performance, with a cross-validated area under the receiver operating characteristic curve of 0.86 (95% CI: 0.82–0.90).
These findings suggest that routine SARS-CoV-2 floor sampling could enhance outbreak detection in hospitals, complementing traditional surveillance methods. Given the strong association between floor contamination and COVID-19 outbreaks, especially in healthcare worker-only areas, this approach could improve infection control strategies. Future research should explore the feasibility of integrating built environment sampling into routine hospital infection prevention protocols and assess its cost-effectiveness in clinical practice.
Reference
Fralick M et al. SARS-CoV-2 burden on the floor was associated with COVID-19 cases and outbreaks in two acute care hospitals: a prospective cohort study. Infect Control Hosp Epidemiol. 2024. DOI: 10.1017/ice.2024.121.
