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Assessment of Air Contamination by SARS-CoV-2 in Hospital Settings

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Key Points

Question  What is the level of air contamination from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different hospital areas, and what factors are associated with contamination?

Findings  In this systematic review of 24 studies, 17% of air sampled from close patient environments was positive for SARS-CoV-2 RNA, with viability of the virus found in 9% of cultures.

Meaning  In this study, air both close to and distant from patients with coronavirus disease 2019 was frequently contaminated with SARS-CoV-2 RNA; however, few of these samples contained viable viruses.

Abstract

Importance  Controversy remains regarding the transmission routes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Objective  To review current evidence on air contamination with SARS-CoV-2 in hospital settings and the factors associated with contamination, including viral load and particle size.

Evidence Review  The MEDLINE, Embase, and Web of Science databases were systematically queried for original English-language articles detailing SARS-CoV-2 air contamination in hospital settings between January 1 and October 27, 2020. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. The positivity rate of SARS-CoV-2 viral RNA and culture were described and compared according to the setting, clinical context, air ventilation system, and distance from patients. The SARS-CoV-2 RNA concentrations in copies per meter cubed of air were pooled, and their distribution was described by hospital areas. Particle sizes and SARS-CoV-2 RNA concentrations in copies or median tissue culture infectious dose (TCID50) per meter cubed were analyzed after categorization as less than 1 μm, from 1 to 4 μm, and greater than 4 μm.

Findings  Among 2284 records identified, 24 cross-sectional observational studies were included in the review. Overall, 82 of 471 air samples (17.4%) from close patient environments were positive for SARS-CoV-2 RNA, with a significantly higher positivity rate in intensive care unit settings (intensive care unit, 27 of 107 [25.2%] vs non–intensive care unit, 39 of 364 [10.7%]; P < .001). There was no difference according to the distance from patients (≤1 m, 3 of 118 [2.5%] vs >1-5 m, 13 of 236 [5.5%]; P = .22). The positivity rate was 5 of 21 air samples (23.8%) in toilets, 20 of 242 (8.3%) in clinical areas, 15 of 122 (12.3%) in staff areas, and 14 of 42 (33.3%) in public areas. A total of 81 viral cultures were performed across 5 studies, and 7 (8.6%) from 2 studies were positive, all from close patient environments. The median (interquartile range) SARS-CoV-2 RNA concentrations varied from 1.0 × 103 copies/m3 (0.4 × 103 to 3.1 × 103 copies/m3) in clinical areas to 9.7 × 103 copies/m3 (5.1 × 103 to 14.3 × 103 copies/m3) in the air of toilets or bathrooms. Protective equipment removal and patient rooms had high concentrations per titer of SARS-CoV-2 (varying from 0.9 × 103 to 40 × 103 copies/m3 and 3.8 × 103 to 7.2 × 103 TCID50/m3), with aerosol size distributions that showed peaks in the region of particle size less than 1 μm; staff offices had peaks in the region of particle size greater than 4 μm.

Conclusions and Relevance  In this systematic review, the air close to and distant from patients with coronavirus disease 2019 was frequently contaminated with SARS-CoV-2 RNA; however, few of these samples contained viable viruses. High viral loads found in toilets and bathrooms, staff areas, and public hallways suggest that these areas should be carefully considered.

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Article Information

Accepted for Publication: November 18, 2020.

Published: December 23, 2020. doi:10.1001/jamanetworkopen.2020.33232

Correction: This article was corrected on January 26, 2021, to fix an error in Figure 3.

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Birgand G et al. JAMA Network Open.

Corresponding Author: Gabriel Birgand, PhD, Centre Hospitalo-Universitaire de Nantes, 5 rue du Professeur Yves Boquien, 44093 Nantes, France (gabriel.birgand@chu-nantes.fr).

Author Contributions: Dr Birgand had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Birgand, Peiffer-Smadja, Fournier, Lucet.

Acquisition, analysis, or interpretation of data: Birgand, Peiffer-Smadja, Fournier, Kerneis, Lescure.

Drafting of the manuscript: Birgand, Fournier, Lucet.

Critical revision of the manuscript for important intellectual content: Birgand, Peiffer-Smadja, Kerneis, Lescure.

Statistical analysis: Birgand.

Supervision: Lescure, Lucet.

Conflict of Interest Disclosures: Dr Kerneis reported receiving personal fees, grants, and nonfinancial support from bioMérieux, travel fees from Accelerate Diagnostics, and personal fees from MSD outside the submitted work. Dr Lescure reported receiving personal fees from bioMérieux, Gilead, and MSD outside the submitted work. No other disclosures were reported.

Funding/Support: The research was funded by the National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infection and Antimicrobial Resistance at Imperial College London in partnership with Public Health England. The support of Economic and Social Research Council as part of the Antimicrobial Cross Council initiative supported by the 7 UK research councils and also the support of the Global Challenges Research Fund is gratefully acknowledged.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The views expressed are those of the authors and not necessarily those of the National Health Service, the National Institute for Health Research, the Department of Health, or Public Health England.

Meeting Presentation: These results have been presented at the virtual ESCMID Conference on Coronavirus Disease (ECCVID); September 23, 2020.

Additional Contributions: Marta Castrica, MSc (Department of Health, Animal Science and Food Safety VESPA, University of Milan, UNIMI), and Laura Menchetti, MSc (Faculty of Veterinary Medicine, Università degli Studi di Perugia, UNIPG) assisted with data collection. They were not compensated for their time.

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