Distribution of SARS-CoV-2 RNA signal in a home with COVID-19 positive occupants

Abstract

Although many COVID-19 patients isolate and recover at home, the dispersal of SARS-CoV-2 onto surfaces and dust within the home environment remains poorly understood. To investigate the distribution and persistence of SARS-CoV-2 in a home with COVID-19 positive occupants, samples were collected from a household with two confirmed COVID-19 cases (one adult and one child). Home surface swab and dust samples were collected two months after symptom onset (and one month after symptom resolution) in the household. The strength of the SARS-CoV-2 molecular signal in fomites varied as a function of sample location, surface material and cleaning practices. Notably, the SARS-CoV-2 RNA signal was detected at several locations throughout the household although cleaning appears to have attenuated the signal on many surfaces. Of the 24 surfaces sampled, 46% were SARS-CoV-2 positive at the time of sampling. The SARS-CoV-2 concentrations in dust recovered from floor and HVAC filter samples ranged from 10 4 -10 5 N2 gene copies/g dust. While detection of viral RNA does not imply infectivity, this study confirms that the SARS-CoV-2 RNA signal can be detected at several locations within a COVID-19 isolation home and can persist after symptoms have resolved. In addition, the concentration of SARS-CoV-2 (normalized per unit mass of dust) recovered in home HVAC filters may prove useful for estimating SARS-CoV-2 airborne levels in homes. In this work, using the quantitative filter forensics methodology, we estimated an average integrated airborne SARS-CoV-2 concentration of 69 ± 43 copies/m 3 . This approach can be used to help building scientists and engineers develop best practices in homes with COVID-19 positive occupants.

The challenge of SARS-CoV-2 environmental monitoring in schools using floors and portable HEPA filtration units: Fresh or relic RNA?

“…The intermittent and repeated positives could have been a result of the resuspension of dust particles containing SARS-CoV-2 genetic material. SARS-CoV-2 RNA has been detected in floor and HVAC dust up to two months after patient symptom onset (Maestre et al, 2021), which could explain our results in the absence of clinical confirmation due to the low testing participation.…”

“…These preliminary results provided further evidence for the stability of SARS-CoV-2 RNA in the environment at least six days after deposition and validated the potential use of portable HEPA filters for environmental monitoring of COVID-19. Environmental monitoring for the presence of SARS-CoV-2 RNA through air sampling has been demonstrated in clinical and transportation settings using diverse air samplers (Barbieri et al, 2021;Moreno et al, 2021), and by swabbing or vacuuming HVAC systems (Maestre et al, 2021;Moreno et al, 2021). However, acquiring and deploying air samplers is challenging due to high costs and noise levels of these instruments.…”

“…Environmental sampling for SARS-CoV-2 through high-touch surface testing has been examined by both academic research-based projects (Zhou et al, 2020;Harvey et al, 2021) as well as via companies offering monitoring services (Marshall et al, 2020). Several groups, including ours, have also evaluated viral RNA in HVAC systems with mixed results (Mouchtouri et al, 2020;Nissen et al, 2020;Coil et al, 2021;Horve et al, 2021;Maestre et al, 2021) or with portable air samplers (Ang et al, 2021). Complexities of HVAC systems (e.g., shared air between rooms, timed operation, difficult to access, variable filter types) have prevented filter-based monitoring from being widely deployed.…”

Effects of face masks and ventilation on the risk of SARS-CoV-2 respiratory transmission in public toilets: a quantitative microbial risk assessment

“…Communal confined spaces such as public toilets in shopping centers, schools, restaurants, airports, theaters, and hospitals may be significant areas for SARS-CoV-2 transmission (Dancer, Li, et al, 2021). Surface contamination with SARS-CoV-2 in toilets and bathrooms has been reported (Ding, Qian, et al, 2021;Maestre, Jarma, et al, 2021); however, transmission risks from fomite exposure could be reduced significantly through the simple yet effective interventions of hand washing, hand sanitizing, and surface disinfection (Dancer et al, 2021;World Health Organization [WHO], 2020a; Pitol & Julian, 2021). Airborne transmission, on the other hand, is deemed the main route of COVID-19 spread (Centers for Disease Control and Prevention, 2021) and could be aggravated by the use of busy, confined public toilet spaces, especially if appropriate steps are not taken to mitigate the risk of virus transmission (Dancer, Li, et al, 2021).…”

Public Buses Decontamination by Automated Hydrogen Peroxide Aerosolization System

“…A modeling study of the spread ability by fomite transmission in aircraft showed that most of the high-touch surfaces in the cabin were contaminated within 2 or 3 h [18]. Many studies have found environments contaminated with SAR-CoV-2 in both health-care settings [19], [20], [21], [22], [23] and non-health-care settings [24], [25], [26], [27], [28], [29]. The evidence showed that SARS-CoV-2 could persist on surfaces for several hours or days [30].…”