Detection of Covid-19 Outbreaks Using Built Environment Testing for SARS-CoV-2

Area of Science:

• Environmental microbiology
• Infectious disease epidemiology
• Public health surveillance

Background:

• Wastewater surveillance is established for population-level SARS-CoV-2 monitoring.
• Built environment sampling offers potential for spatially refined surveillance in congregate settings.
• Long-term care homes (LTCHs) are vulnerable to infectious disease outbreaks.

Purpose of the Study:

• To investigate the utility of SARS-CoV-2 detection on floor surfaces for early outbreak identification in LTCHs.
• To assess the association between floor contamination and coronavirus disease 2019 (COVID-19) outbreaks.

Main Methods:

• Prospective study in 10 LTCHs over 14 months (September 2021-November 2022).
• Weekly sampling of floor surfaces at multiple locations within each facility.
• Analysis of SARS-CoV-2 presence using quantitative reverse transcriptase polymerase chain reaction (RT-qPCR).

Main Results:

• A total of 4895 swabs were collected; 23 COVID-19 outbreaks occurred.
• Floor swab positivity was significantly higher during outbreak periods (54.3%) versus non-outbreak periods (22.3%).
• Positive floor swabs exceeding 10% preceded outbreak identification by at least 5-10 days in most cases.

Conclusions:

• Detection of SARS-CoV-2 on floor surfaces is strongly correlated with COVID-19 outbreaks in LTCHs.
• Floor sampling demonstrates potential as a tool for enhancing early outbreak detection in these settings.
• This method could facilitate timely implementation of control measures to mitigate transmission.