Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients
Abstract
Background
There currently is substantial controversy about the role played by SARS-CoV-2 in aerosols in disease transmission, due in part to detections of viral RNA but failures to isolate viable virus from clinically generated aerosols.
Methods
Air samples were collected in the room of two COVID-19 patients, one of whom had an active respiratory infection with a nasopharyngeal (NP) swab positive for SARS-CoV-2 by RT-qPCR. By using VIVAS air samplers that operate on a gentle water-vapor condensation principle, material was collected from room air and subjected to RT-qPCR and virus culture. The genomes of the SARS-CoV-2 collected from the air and of virus isolated in cell culture from air sampling and from a NP swab from a newly admitted patient in the room were sequenced.
Findings
Viable virus was isolated from air samples collected 2 to 4.8m away from the patients. The genome sequence of the SARS-CoV-2 strain isolated from the material collected by the air samplers was identical to that isolated from the NP swab from the patient with an active infection. Estimates of viable viral concentrations ranged from 6 to 74 TCID 50 units/L of air.
Interpretation
Patients with respiratory manifestations of COVID-19 produce aerosols in the absence of aerosol-generating procedures that contain viable SARS-CoV-2, and these aerosols may serve as a source of transmission of the virus.
Funding
Partly funded by Grant No. 2030844 from the National Science Foundation and by award 1R43ES030649 from the National Institute of Environmental Health Sciences of the National Institutes of Health, and by funds made available by the University of Florida Emerging Pathogens Institute and the Office of the Dean, University of Florida College of Medicine.
Research in context
Evidence before this study
Various studies report detection of SARS-CoV-2 in material collected by air samplers positioned in clinics and in some public spaces. For those studies, detection of SARS-CoV-2 has been by indirect means; instead of virus isolation, the presence of the virus in material collected by air samplers has been through RT-PCR detection of SARS-CoV-2 RNA. However, questions have been raised about the clinical significance of detection of SARS-CoV-2 RNA, particularly as airborne viruses are often inactivated by exposure to UV light, drying, and other environmental conditions, and inactivated SARS-CoV-2 cannot cause COVID-19.
Added value of this study
Our virus isolation work provides direct evidence that SARS-CoV-2 in aerosols can be viable and thus pose a risk for transmission of the virus. Furthermore, we show a clear progression of virus-induced cytopathic effects in cell culture, and demonstrate that the recovered virus can be serially propagated. Moreover, we demonstrate an essential link: the viruses we isolated in material collected in four air sampling runs and the virus in a newly admitted symptomatic patient in the room were identical. These findings strengthen the notion that airborne transmission of viable SARS-CoV-2 is likely and plays a critical role in the spread of COVID-19.
Implications of all the available evidence
Scientific information on the mode of transmission should guide best practices Current best practices for limiting the spread of COVID-19. Transmission secondary to aerosols, without the need for an aerosol-generating procedure, especially in closed spaces and gatherings, has been epidemiologically linked to exposures and outbreaks. For aerosol-based transmission, measures such as physical distancing by 6 feet would not be helpful in an indoor setting and would provide a false-sense of security. With the current surges of cases, to help stem the COVID-19 pandemic, clear guidance on control measures against SARS-CoV-2 aerosols are needed.
Article activity feed
-
SciScore for 10.1101/2020.08.03.20167395: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: An abbreviated summary of methods is provided below: Institutional Review Board (IRB) approval and patients: The study protocol was approved by the UF IRB (study IRB202002102). Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Cell Line Authentication not detected. Table 2: Resources
Experimental Models: Cell Lines Sentences Resources 23 Next-generation sequencing the genome of SARS-CoV-2 isolated from NP swab: The vRNA extracted from virions in spent Vero E6 cell culture medium served as a template to generate a cDNA library using a NEBNext Ultra II RNA Library Prep kit (New England Biolabs, Inc.) V…SciScore for 10.1101/2020.08.03.20167395: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement IRB: An abbreviated summary of methods is provided below: Institutional Review Board (IRB) approval and patients: The study protocol was approved by the UF IRB (study IRB202002102). Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Cell Line Authentication not detected. Table 2: Resources
Experimental Models: Cell Lines Sentences Resources 23 Next-generation sequencing the genome of SARS-CoV-2 isolated from NP swab: The vRNA extracted from virions in spent Vero E6 cell culture medium served as a template to generate a cDNA library using a NEBNext Ultra II RNA Library Prep kit (New England Biolabs, Inc.) Vero E6suggested: RRID:CVCL_XD71)Software and Algorithms Sentences Resources Following the removal of host sequences (Chlorocebus sabaeus; GenBank assembly accession number GCA_000409795.2) using Kraken 2,29 de novo assembly of paired-end reads was performed in SPAdes v3.13.0 with default parameters. Krakensuggested: (Kraken, RRID:SCR_005484)SPAdessuggested: (SPAdes, RRID:SCR_000131)Results from OddPub: Thank you for sharing your data.
Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
-
