Contamination of air and surfaces in workplaces with SARS-CoV-2 virus: a systematic review

Cherrie, John W.; Cherrie, Mark; Davis, A. Porter; Holmes, David; Semple, Sean; Steinle, Susanne; Macdonald, Ewan; Moore, Ginny; Loh, Miranda

doi:10.1101/2021.01.25.21250233

Cited by 10 publications

(13 citation statements)

References 47 publications

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“…1,[5][6][7][10][11][12] A limited number of studies to date have recovered viable SARS-CoV-2 virus from environmental samples. 14 We attempted to recover SARS-CoV-2 virus from 42 environmental surface samples, six (14%) of which from three (4%) patients yielded viable virus; positive cultures were confirmed with SARS-CoV-2 RT-PCR. Notably, all surface samples that yielded viable virus were collected from patients within 5 days of illness onset.…”

Section: Discussionmentioning

confidence: 99%

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Surface and air contamination with SARS-CoV-2 from hospitalized COVID-19 patients in Toronto, Canada

Kotwa

Jamal

Mbareche

et al. 2021

Preprint

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Background The aim of this prospective cohort study was to determine the burden of SARS-CoV-2 in air and on surfaces in rooms of patients hospitalized with COVID-19, and to identify patient characteristics associated with SARS-CoV-2 environmental contamination. Methods Nasopharyngeal swabs, surface, and air samples were collected from the rooms of 78 inpatients with COVID-19 at six acute care hospitals in Toronto from March to May 2020. Samples were tested for SARS-CoV-2 viral RNA and cultured to determine potential infectivity. Whole viral genomes were sequenced from nasopharyngeal and surface samples. Association between patient factors and detection of SARS-CoV-2 RNA in surface samples were investigated using a mixed-effects logistic regression model. Findings SARS-CoV-2 RNA was detected from surfaces (125/474 samples; 42/78 patients) and air (3/146 samples; 3/45 patients) in COVID-19 patient rooms; 14% (6/42) of surface samples from three patients yielded viable virus. Viral sequences from nasopharyngeal and surface samples clustered by patient. Multivariable analysis indicated hypoxia at admission, a PCR-positive nasopharyngeal swab with a cycle threshold of ≤30 on or after surface sampling date, higher Charlson co-morbidity score, and shorter time from onset of illness to sample date were significantly associated with detection of SARS-CoV-2 RNA in surface samples. Interpretation The infrequent recovery of infectious SARS-CoV-2 virus from the environment suggests that the risk to healthcare workers from air and near-patient surfaces in acute care hospital wards is likely limited. Surface contamination was greater when patients were earlier in their course of illness and in those with hypoxia, multiple co-morbidities, and higher SARS-CoV-2 RNA concentration in NP swabs. Our results suggest that, while early detection and isolation of COVID-19 patients is important, air and surfaces may pose limited risk a few days after admission to acute care hospitals.

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Section: Discussionmentioning

confidence: 99%

“…[3][4][5][6][7][8][9][10][11][12] However, a minority of studies have attempted to culture virus. 13,14 This limits our understanding of exposure and transmission risk.…”

Section: Introductionmentioning

confidence: 99%

Surface and air contamination with SARS-CoV-2 from hospitalized COVID-19 patients in Toronto, Canada

Kotwa

Jamal

Mbareche

et al. 2021

Preprint

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“…We identified one non-peer-reviewed (pre-print) systematic review that assessed SARS-CoV-2 contamination in fomites 18 . The authors concluded that the quality of measurements was poor, and the reliability of the data is uncertain.…”

Section: Discussionmentioning

confidence: 99%

SARS-CoV-2 and the role of fomite transmission: a systematic review

et al. 2021

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Background: SARS-CoV-2 RNA has been detected in fomites which suggests the virus could be transmitted via inanimate objects. However, there is uncertainty about the mechanistic pathway for such transmissions. Our objective was to identify, appraise and summarise the evidence from primary studies and systematic reviews assessing the role of fomites in transmission. Methods: This review is part of an Open Evidence Review on Transmission Dynamics of SARS-CoV-2. We conduct ongoing searches using WHO Covid-19 Database, LitCovid, medRxiv, and Google Scholar; assess study quality based on five criteria and report important findings on an ongoing basis. Results: We found 64 studies: 63 primary studies and one systematic review (n=35). The settings for primary studies were predominantly in hospitals (69.8%) including general wards, ICU and SARS-CoV-2 isolation wards. There were variations in the study designs including timing of sample collection, hygiene procedures, ventilation settings and cycle threshold. The overall quality of reporting was low to moderate. The frequency of positive SARS-CoV-2 tests across 51 studies (using RT-PCR) ranged from 0.5% to 75%. Cycle threshold values ranged from 20.8 to 44.1. Viral concentrations were reported in 17 studies; however, discrepancies in the methods for estimation prevented comparison. Eleven studies (17.5%) attempted viral culture, but none found a cytopathic effect. Results of the systematic review showed that healthcare settings were most frequently tested (25/35, 71.4%), but laboratories reported the highest frequency of contaminated surfaces (20.5%, 17/83). Conclusions: The majority of studies report identification of SARS-CoV-2 RNA on inanimate surfaces; however, there is a lack of evidence demonstrating the recovery of viable virus. Lack of positive viral cultures suggests that the risk of transmission of SARS-CoV-2 through fomites is low. Heterogeneity in study designs and methodology prevents comparisons of findings across studies. Standardized guidelines for conducting and reporting research on fomite transmission is warranted.

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“…There are limited data about the exposure of workers to the SARS-CoV-2 virus. Most research concerns virus in healthcare settings, where air concentrations and surface contamination were generally low ( Cherrie et al , 2021 ). It is unclear why this is the case, but it may reflect good general ventilation and regular cleaning regimes in these workplaces.…”

Section: Methodsmentioning

confidence: 99%

“…It is unclear why this is the case, but it may reflect good general ventilation and regular cleaning regimes in these workplaces. Very limited data are available for public transportation, which also show low levels of air and surface contamination ( Cherrie et al , 2021 ). There are no data on environmental contamination for other workplace environments.…”

Section: Methodsmentioning

confidence: 99%

The Development of a COVID-19 Control Measures Risk Matrix for Occupational Hygiene Protective Measures

Williams

Cherrie

Dobbie

et al. 2021

Annals of Work Exposures and Health

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The British Occupational Hygiene Society (BOHS) Covid-19 Working Group developed a control banding matrix to provide guidance for employers and others to help assess the risks of Covid-19 infection during the pandemic. The matrix was based on occupational hygiene principles and the judgement of the occupational health practitioners involved; since objective data on workers’ exposure were unavailable. Users of the matrix identify one of five exposure categories based on generic job descriptions and example occupations, and these categories are linked to generic guidance on interventions at source, on the exposure pathway and for individual workers. The risk matrix was published on the BOHS website and the guidance has been downloaded more than 2000 times. The matrix has had limited evaluation for reliability, but the data suggest that the highest exposure ranked jobs were associated with higher age-standardized mortality in Britain during the pandemic. However, there was considerable variability in exposure assignments between assessors, which underlines the need for the control guidance to be precautionary. The BOHS calls on academic researchers to undertake further work to validate the reliability of the tool.

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Contamination of air and surfaces in workplaces with SARS-CoV-2 virus: a systematic review

Cited by 10 publications

References 47 publications

Surface and air contamination with SARS-CoV-2 from hospitalized COVID-19 patients in Toronto, Canada

Surface and air contamination with SARS-CoV-2 from hospitalized COVID-19 patients in Toronto, Canada

SARS-CoV-2 and the role of fomite transmission: a systematic review

The Development of a COVID-19 Control Measures Risk Matrix for Occupational Hygiene Protective Measures

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