A recent research study carried out in Ontario, Canada indicates a strong correlation between the density of SARS-CoV-2 (the virus responsible for COVID-19) on hospital floor surfaces and outbreaks of the disease. The findings suggest that an increase in floor viral load by 10-fold enhances the likelihood of a COVID-19 outbreak by an impressive 22-fold. This crucial revelation emphasizes the role of regular floor sampling as an essential component of localized virus surveillance.
Adding another layer of monitoring, floor testing for SARS-CoV-2 can crucially inform the implementation and advancement of local infection prevention and control measures.
This study extends upon previous research by the same team, which initially discovered the correlation between floor viral density and COVID-19 outbreaks in long-term care homes. Currently, wastewater detection stands as the best-known method for environmental surveillance of COVID-19. The team proposes floor swabbing as another low-cost, feasible approach to surveillance.
According to Caroline Nott, MD, and a senior researcher on the team, wastewater surveillance provides a city-wide overview but fails to depict a detailed snapshot of individual hospital wards. The research team advocates for floor swabbing as an additional tool for reviewing the built environment and predicting potential viral hotspots, enabling more precise preventional actions including selective room closures rather than shutting down whole wards.
In the study at hand, the researchers tested floor surfaces at two Ontario hospitals between July 2022 and March 2023. The test sites were healthcare-worker exclusive areas across four adult inpatient wards, where a large proportion of 71% of the 760 floor swabs returned positive for SARS-CoV-2 RNA. A total of four outbreaks were recorded at the first hospital, while the second hospital reported seven COVID-19 outbreaks.
Despite the promising findings, the researchers are aware of potential limitations. Steven Rogak, PhD, Professor of Mechanical Engineering at UBC, noted certain variables such as HVAC systems and air purifiers in hospitals might lead to lower aerosol counts but higher droplet deposition on floors, potentially skewing results. Moreover, care would need to be taken about when and where to perform the floor swabbing to avoid false negatives, such as swabbing just after the floors have been cleaned.
While further refinement might be required for widespread application, Rogak believes the method holds potential for becoming a standardized technique for monitoring viral loads in hospitals. However, on a cautionary note, Adrian Popp, MD, chair of the Infectious Disease Service at Huntington Hospital–Northwell Health, expressed that finding virus remnants on floors does not necessarily imply infectiousness.
As we continue to navigate the challenges of COVID-19 and potential novel pathogens, studies like these exemplify the need for us to continuously innovate and improve our practices for the benefit of patients and healthcare workers alike.
Tags: COVID-19, infection control, hospital infection surveillance, coronavirus