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Observational Study
. 2021 Nov;42(11):1327-1332.
doi: 10.1017/ice.2021.8. Epub 2021 Jan 25.

Lack of viable severe acute respiratory coronavirus virus 2 (SARS-CoV-2) among PCR-positive air samples from hospital rooms and community isolation facilities

Sean Wei Xiang Ong #  1   2 , Yian Kim Tan #  3 , Kristen Kelli Coleman #  4   5 , Boon Huan Tan  3 , Yee-Sin Leo  1   2   5   6 , Dong Ling Wang  3 , Ching Ging Ng  3 , Oon-Tek Ng  1   2   6 , Michelle Su Yen Wong  3 , Kalisvar Marimuthu  1   2   5   7
Affiliations
Observational Study

Lack of viable severe acute respiratory coronavirus virus 2 (SARS-CoV-2) among PCR-positive air samples from hospital rooms and community isolation facilities

Sean Wei Xiang Ong et al. Infect Control Hosp Epidemiol. 2021 Nov.

Abstract

Background: Understanding the extent of aerosol-based transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is important for tailoring interventions for control of the coronavirus disease 2019 (COVID-19) pandemic. Multiple studies have reported the detection of SARS-CoV-2 nucleic acid in air samples, but only one study has successfully recovered viable virus, although it is limited by its small sample size.

Objective: We aimed to determine the extent of shedding of viable SARS-CoV-2 in respiratory aerosols from COVID-19 patients.

Methods: In this observational air sampling study, air samples from airborne-infection isolation rooms (AIIRs) and a community isolation facility (CIF) housing COVID-19 patients were collected using a water vapor condensation method into liquid collection media. Samples were tested for presence of SARS-CoV-2 nucleic acid using quantitative real-time polymerase chain reaction (qRT-PCR), and qRT-PCR-positive samples were tested for viability using viral culture.

Results: Samples from 6 (50%) of the 12 sampling cycles in hospital rooms were positive for SARS-CoV-2 RNA, including aerosols ranging from <1 µm to >4 µm in diameter. Of 9 samples from the CIF, 1 was positive via qRT-PCR. Viral RNA concentrations ranged from 179 to 2,738 ORF1ab gene copies per cubic meter of air. Virus cultures were negative after 4 blind passages.

Conclusion: Although SARS-CoV-2 is readily captured in aerosols, virus culture remains challenging despite optimized sampling methodologies to preserve virus viability. Further studies on aerosol-based transmission and control of SARS-CoV-2 are needed.

Keywords: COVID-19; SARS-CoV-2; aerosols; air sampling; airborne; viral culture.

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Figures

Fig. 1.
Fig. 1.
Air sampling set-up in hospital airborne-infection isolation room.
Fig. 2.
Fig. 2.
Air sampling set-up in community isolation facility cubicle.
See this image and copyright information in PMC

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