Rees Kassen, PhD

Director, CoVaRR-Net’s Coronavirus in the Urban Built Environment (CUBE) project
Member, CoVaRR-Net Computational Analysis, Modelling and Evolutionary Outcomes (CAMEO) Pillar
Professor, University of Ottawa

Caroline Nott, MD

Collaborator, CoVaRR-Net’s Coronavirus in the Urban Built Environment (CUBE) project
Clinical Investigator, Ottawa Hospital Research Institute
Director, Antimicrobial Stewardship Program, The Ottawa Hospital
Assistant Professor, University of Ottawa

Given that PCR testing of individuals for COVID-19 and case reporting have declined in Canada, public health officials have relied increasingly on wastewater sampling and seroprevalence testing as useful surveillance tools for tracking the spread of SARS-CoV-2 and predicting outbreaks in large geographic areas, such as communities. But these methods aren’t as useful in tracking SARS-CoV-2 at a smaller scale, such as a hospital, school, workplace, or long-term care home, or in areas within those buildings.

Surface environmental testing is a spatially refined detection tool that complements wastewater sampling for tracking SARS-CoV-2, influenza, and other viruses

“Surface environmental testing for SARS-CoV-2, especially on floors, is a new and effective tool that can rapidly identify where SARS-CoV-2 is present in buildings and track its prevalence over time,” says Dr. Rees Kassen, Director of CoVaRR-Net’s Coronavirus in the Urban Built Environment (CUBE) project, Member of CoVaRR-Net’s Computational Analysis, Modelling and Evolutionary Outcomes (CAMEO) Pillar, and Professor of Evolutionary Biology at the University of Ottawa.

“This innovative method is fast, easy, affordable, non-invasive and can be done at a small scale to fill in the information gaps between individual testing, seroprevalence testing and wastewater sampling. You can target your surveillance to specific locations for SARS-CoV-2. We could also use floor sampling to identify and track the presence of other respiratory pathogens, such as influenza and respiratory syncytial virus (RSV), which affects young children, and emerging pathogens, such as mpox,” adds Dr. Kassen.

Floors act like sinks and are reliable surfaces for built environment testing

In recent studies of hospitals and long-term care homes, the CUBE research team discovered and demonstrated that floors are the most reliable surface for collecting samples and testing for the presence of SARS-CoV-2 in people working, living, or receiving care in a building, or specific areas within it. When a person infected with COVID-19 breathes, speaks, coughs or sneezes, the virus travels outward in the respiratory particles, remains suspended in the air for a time and eventually falls and settles on the floor. Swab samples taken from floors undergo PCR testing and can indicate whether and how much of the virus is present in a specific room or building.

“The floor acts as a sink where the virus accumulates,” explains Dr. Caroline Nott, Collaborator, CoVaRR-Net’s Coronavirus in the Urban Built Environment (CUBE) project, Director of the Antimicrobial Stewardship Program at The Ottawa Hospital and Assistant Professor, University of Ottawa. “Since high-touch surfaces like door handles, elevator buttons and computer keyboards are cleaned more frequently, sampling floors measures the presence and spread of SARS-CoV-2 more accurately and reliably. We found that signals from sampling the presence and amount of virus on the floor accurately tracked cases and outbreaks in hospitals and long-term care homes, and floor samples can be a reliable marker of outbreaks and disease burden in the environment.”

CUBE’s studies also show that floor sampling can detect the virus up to a week before cases are reported, which can help to inform infection control decisions and potentially prevent or contain outbreaks. “When you see a rise in positive results from environmental testing, this should set off a red flag or early-warning signal to implement measures to safeguard people and reduce the spread of the virus. If you were managing a factory, a warehouse, an office, or a long-term care facility, you would pay attention and might want to do targeted individual testing, for example,” says Dr. Kassen.

Surface sampling can provide results that are directly actionable in different settings. “In a long-term care home, surface sampling can provide data to identify an impending but clinically undetected outbreak and help in monitoring whether an outbreak is worsening, improving, or resolved. If you were swabbing and found no positive signal, you might be reassured things are good and potentially be able to keep units open and people active. We think this method could also be very useful in workplaces and schools,” says Dr. Nott.

Testing surface sampling for monitoring COVID-19 in children and adults across diverse community settings

CUBE is now conducting a larger and more ambitious, community-wide environmental surveillance study for SARS-CoV-2 and variants across six geographically distinct regions in the Ottawa area, funded by CoVaRR-Net. “We’re testing the reliability and effectiveness of floor sampling for three distinct populations in different settings in the community: children in elementary schools, healthy adults in congregate settings such as public libraries, and people who are sick in critical care and emergency department waiting rooms in hospitals. The Ottawa study provides an ideal test case to evaluate whether floor sampling could be used as a valuable viral surveillance tool, along with wastewater sampling, seroprevalence testing and targeted individual testing, across the country during this pandemic and in preparing for future pandemics,” says Dr. Kassen.

To arrange an interview with Rees Kassen, or Caroline Nott, please contact: